Novatek-electro OM-310 User manual

NOVATEK-ELECTRO LTD
Research-and-Manufacture Company
POWER LIMITER
OM-310
USERS MANUAL
www.novatek-electro.com

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ОМ-310 NOVATEK-ELECTRO
CONTENT
1. DESCRIPTION AND OPERATION ....................................................................................................................................3
1.1 APPLICATION..............................................................................................................................................................3
1.1.1 OM-310 power limiter is designed for the following applications:.........................................................................3
1.1.2 OM-310 application limitations and proper selection of parameters.....................................................................3
1.1.3 Integrated relays output terminals specification....................................................................................................4
1.1.4 List of abbreviations used .....................................................................................................................................4
1.2 TECHNICAL BRIEF......................................................................................................................................................4
1.2.1 Basic technical parameters ..................................................................................................................................4
1.2.2 Measured and calculated parameters ..................................................................................................................4
1.2.3 Programmable parameters and their variability ranges .......................................................................................6
1.2.4 Operating controls and the dimensions of the ОМ-310 .......................................................................................9
1.2.5 Power Limiting Functions....................................................................................................................................10
1.2.6 Protection functions............................................................................................................................................12
1.3 PRODUCT PACKAGE CONTENTS...........................................................................................................................13
1.4 EQUIPMENT FEATURES AND OPERATION...........................................................................................................13
2. INTENDED USE ...............................................................................................................................................................13
2.1. SAFETY.....................................................................................................................................................................13
2.2 ОМ-310 DEVICE CONTROL......................................................................................................................................13
2.2.1 Control Modes.....................................................................................................................................................13
2.2.2 Disabled keypad mode........................................................................................................................................14
2.2.3 MMSP mode ......................................................................................................................................................14
2.2.4 User level ...........................................................................................................................................................14
2.2.5 Service Engineer Level.......................................................................................................................................14
2.2.6 Restoring factory settings...................................................................................................................................15
2.3 OM-310 PRE-OPERATION PROCEDURE................................................................................................................15
2.4 INTENDED USE.........................................................................................................................................................16
2.4.1 ОМ-310 operation before load relay closure......................................................................................................16
2.4.2 OM-310 operation before load relay closure.......................................................................................................17
2.4.3 Characterizing relay operation ............................................................................................................................17
2.4.4 Work with RS-232/RS-485 interface under MODBUS protocol in RTU mode....................................................17
2.4.5 The load energize/de-energize remote control via RS-232/RS-485 interface...................................................21
2.4.6 Load energize/de-energize via remote breaker..................................................................................................22
2.4.7 Fault conditions system.......................................................................................................................................22
2.4.8 Faulty conditions log ..........................................................................................................................................22
2.4.9 Load start/cutoff control with use of OM-310 front panel....................................................................................23
3. MAINTENANCE ...............................................................................................................................................................24
3.1. SAFETY.....................................................................................................................................................................24
3.2 MAINTENANCE SCHEDULE.....................................................................................................................................24
4. TRANSPORTATION AND STORAGE.............................................................................................................................24
5. PERIOD OF SERVICE, STORAGE, AND MANUFACTURER’S WARRANTY ..............................................................24
6. ACCEPTANCE CERTIFICATE ......................................................................ОШИБКА! ЗАКЛАДКА НЕ ОПРЕДЕЛЕНА.
APPENDIX 1-DEPENDENT TIME DELAY CURRENT BASED PROTECTION TYPES:.................................................25

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NOVATEK-ELECTRO ОМ-310
1. DESCRIPTION AND OPERATION
1.1 APPLICATION
1.1.1 OM-310 power limiter is designed for the following applications:
- load protection at poor parameters of the mains;
- complete load cutoff in case if watts input exceeds the main threshold within the user-set time period;
- partial load cutoff in case if watts input exceeds the additional threshold within the user-set time period;
- measurement and indication of 3-phase electric circuit (delta voltage and mesh voltage RMS values; positive
phase, negative phase and zero phase sequence voltages; phase currents RMS values; input wattage of active
power, wattles power, apparent power, power factor (cos ϕ))
- fault warning;
- remote load on and off via RS-232/RS485 interface or and external switch.
OM-310 provides for operation under loads ranging from 2,5 kW to 30 kW with use of integrated current transfor-
mers, and up to 350 kW at use of external current transformers, including when in networks with insulated neutral.
OM-310 device provides the following types of load protection:
-when the mains voltage is of poor quality (impermissible voltage surges, phase loss, incorrect phase se-
quence and phase "coincidence", phase/line voltage imbalance);
-when maximum specified current in any load phase is exceeded;
-against “ground” leakage currents;
For each separate type of protection, the unit allows to enable or disable automatic load reset (further: AR)
OM-310 provides electric equipment protection by means of a magnetic starter (contactor) coil control.
Using OM-310 the user has possibility tochoose functionality of additional relay and use it for following operations:
-signalization emergency situations
- contactor connection of additional loading
-as time relay
-signalization of reactive power excess
-signalization of active power excess
Communication
ОМ-310 provides for:
- control and parameters transfer via RS-485 interface according to MODBUS protocol,
-control and parameters transfer via RS-232 interface.
N o t e: Simultaneous use of RS-485 and RS-232 is not possible.
Interaction of PC and OM-310 is possible via "OM-310 Control Panel” Software that can be downloaded from
the “Novatek-Electro” website (http://www.novatek-electro.com/production_ом.htm).
OM-310 Control Panel software is dedicated for monitoring status and retrieving data from OM-310 devices via stan-
dard communication interface (RS-232 or RS-485). The Software allows for saving (loading) variousOM-310 settings,
retrieving data and saving them for further research. The user can view saved data in a graph, while comparing pa-
rameters.
The CP graphic environment allows for real-time viewing the current status of various OM-310 parameters.
The flexible interface design allows tuning it to any user’s preferences.
1.1.2 OM-310 application limitations and proper selection of parameters
1.1.2.1 Use of integrated current transformers.
Attention! OM-310 cannot be used for protection of load with wattage over 30 kW.
When measuring load currents from 63A to 300A, the measurement error does not exceed 5%, while at currents
over 320A, the current transformer core saturation starts, and the measurement error increases rapidly. Regardless
In spite of the actual current value, the current measured by OM-310 will not exceed 400A. Setting up certain pro-
grammable parameters (maximum current protection) without regard to current transformers saturation will make
protection tripping impossible.
For example, at “”=50 (load rated current), =0 (ratio of independent delay current protection), =9
(maximum current protection tripping), the maximum current protection would have tripped at current value of 450А.
Due to current transformer saturation, the measured current value will not exceed 380-400A, even in case of a short
circuit from the load side, and currents of over 1000A, and, therefore, ОМ-310 will not de-energize the load. In such
case (“”=50) the user shall set the overcurrent tripping ratio to not more than 6.
1.1.2.2 Use of external currents transformers.
In case of tested standard transformer samples, the core saturation took place at 4-5 times the rated current
value. Therefore, to provide for proper functioning of ОМ-310 protections, one should select external transformers
with rated current value exceeding the rated load currents twice and more, or choose parameters considering the
saturation.

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ОМ-310 NOVATEK-ELECTRO
1.1.3 Integrated relays output terminals specification
The internal relays output terminals specifications are outlined in Table 1.1 and Table 1.2
Table 1.1 - Load relay
Max. current
for U~ 250 V
Number of trips
х1000
Max switching
power
Max sustained safe
AC/DC voltage
Max. current for
U = 30V D.C.
Cos ϕ= 0.4
Cos
ϕ
= 1.0
5 А
8 А
200
100 1000 VА440/125 V 1.3 А
Table 1.2 - Characterizing relay
Max. current
for U~ 250 V
Number of trips
х1000
Max switching
power
Max sustained safe
AC/DC voltage
Max. current for
Uпост = 30V D.C.
Cos ϕ= 0.4
Cos
ϕ
= 1.0
5 А
16 А
400
100 4000 VА440/125 V 3 А
1.1.4 List of abbreviations used
AR – automatic reset
MС– magnetic contactor
PC - personal computer
CT – current transformer
MMSP – mode with minimal number of setting parameters
Itt -rated current of CT. (Specified when external CTs are used. For example, if a CT of T type-0.66 300/5, then
Itt will equal 300А)
In -rated current of load.
1.2 TECHNICAL BRIEF
1.2.1 Basic technical parameters are shown below in table 1.3
Table 1.3 - Basic Technical Parameters
Rated supply voltage: Three-phase 380V 50Hz
Mains frequency, Hz
48-62
Rated load wattage range (during operation with use of integrated current transformers), kW
3-30
Tripping threshold accuracy for wattage, % of rated wattage, at most
5
Tripping threshold accuracy for current, % of rated current, at most
2
Tripping threshold accuracy for voltage, V, at most
3
Phase imbalance detection accuracy for voltage, V, at most
3
Minimum operational voltage:
-single-phase voltage power supply when one phase and neutral wires are connected,V, not less
- three-phase power supply voltage, V, at most
180
450
Analog inputs
- remote switch connection input
- three analog inputs for connecting standard CT with 5A output (of Т-0.66 type or similar)
- input for connecting differential current transformer (zero sequence transformer)
Main outputs
load relay – two groups of changeover contacts -8A 250V cos φ=1;
characterizing relay – one group of changeover contacts -16A 250V at cos φ=1 (the relay
function is assigned by the user);
Power consumption (under load), VA, at most
5,0
Enclosure protection degree: - frame
- terminal block
IP40
IP20
Climate zone version
У3.1 (moderate)
Operating temperature range, °C
from -35 to +55
Storage temperature, °C
from -45 to +70
Weight, kg, at most
0,5
Case dimensions (diagram 1.1) - nine S-type modules
Mounting onto standard 35 mm DIN-rail
Mounting position any
1.2.2 Measured and calculated parameters output to the display unit, their effective range limits and toler-
ances are given below in Table 1.4.
Note: The display device includes:
- two pieces of three-digit, seven segment indicators on OM-310 front panel;

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NOVATEK-ELECTRO ОМ-310
- PC, connected to one of OM-310 interfaces (MODBUS, RS-232).
Table 1.4 - Measured and Displayed Parameters
Measurement functions
Range
Accuracy
Mnemonics
Address
Measurement
units used at
data transfer
Currents
1/10 of an
ampere*
Phase currents RMS values, A
0,5-999
2%


100,101,
102
Zero sequence current RMS value, A
0,3-9,9
2%

103
Each phase average current value at
time specified in tSi parameter


104,105,
106
Мах each phase average current value
obtained (was obtained) since last power
on.
All average values can be reset with
RES/MEM/SEL
button at time of max
average current value output for any
phase (real-
time average current value
for corresponding phase is assigned).
<3 Itt
> 3 Itt
2%
10%



107,108,
109
Negative sequence current (current im-
balance), A.
0,2-200
5%

110
Voltages
Volts
Phase voltages RMS values (defined by
connecting zero wire to OM-310), V
100-300
3 V



111,112
113
Power voltage RMS values, V
100-450
5 В



114,115
116
Positive-sequence voltage, V
100-300
3 B

117
Negative-sequence voltage, V
3 -300
3 B

118
Zero-sequence voltage (vector sum of
three phase voltages,
divided by three),
(measurement is possible only when ze-
ro wire is connected to OM-310),V
3-100
3 B

119
Wattages and Cosines
Gross power, KVA**
0-5000
5%

120, 121
W * 10
Active power, KW**
0-5000
5%

122, 123
Wattles power, KVAr**
0-5000
5%

124, 125
Phase A active power, KW**
0-5000
5%

126, 127
Phase B active power, KW**
0-5000
5%

128, 129
Phase C active power, KW**
0-5000
5%

130, 131
Phase Аvoltage/current angle cosine
0,00-1,00
5%

132
Cosine value
*1000
Phase B voltage/current angle cosine
0,00-1,00
5%

133
Phase C voltage/current angle cosine
0,00-1,00
5%

134
Time before load disconnect tripping when
the load wattage is exceeded, sec ****
0-600
1s

135
seconds
Time before AR delay termination, sec***
0-900
1s

136
Wait time after de-energizing in case of
over wattage (indicates wait time before
permit of system restart ), min ****
0-30
1s

137
Mains frequency, Hz
45-65
1%

138
1/10 Hz

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ОМ-310 NOVATEK-ELECTRO
* Note. When working with external transformers of rated current over 100A, the currents (measured and cal-
culated), except for the zero sequence current (ground fault) are transferred via RS-232/RS485 in amperes.
** Note. If power consumed by the load is over 999 kW (kVA, kVAr), then MW (MVA, MVAr) is displayed on
screen with a “п” – shaped point in the middle position. For instance, if the display shows 3п4”, it means 3.4
MW (MVA, MVAr).
*** Note. If automatic reset is forbidden, "not" message is displayed.
**** Note. If the time is not defined, "---" is displayed on screen.
1.2.3 Programmable parameters and their variability ranges are shown below in table 1.5.
Table 1.5 - Programmable parameters
Settings and read-off
parameters
Code pa-
rameters
Minimum
values
Max.
values
Default
setting
Operation
Address
Transformers
CT in use

0
1
0
0-intergrated CT are in use
1-external CTs are in use
150
CT rated current, A

20
800
100
For an external CT
151
CT rated current, A

5
700
10
Used for calsculating the current and
the time of overcurrent protection
152
Power Control
Rated
power
of load, kW

3
450
5
153
Power limiter tripping
thresholds calculation
parameter

0
2
0
0 – threshold calculation for each
phase (power handling capability for
each phase equals Pnn/3)
1 – threshold calculation for each
phase +20% (total power for al pha-
ses equals Pnn, but not more than
Pnn*1,2/3 for each phase)
2 – aggregate threshold calculation
(total power for all phases equals Pnn)
154
Main threshold, %

50
150
110
155
Additional threshold*, %

30
100
90
156
Time before load relay
de-energizing, sec
(main threshold)

0
300
60
Time before load disconnect tripping
when the load wattage main threshold
is exceeded
157
Time while load relay is
open, min
(main threshold)

1
60
5
Time during which load relay is open
after tripping when the load wattage
main threshold is exceeded
158
Time before characteriz-
ing relay de-energizing*,
sec
(additional threshold)

0
300
10
Time after which the characterizing re-
lay will open after tripping when the
load wattage main threshold is ex-
ceeded
159
Time while the charac-
terizing relay is open,
min (additional thre-
shold)

1
60
5
Time during which the characterizing
relay is open after tripping which take
place when the load wattage main
threshold is exceeded
160
Additional threshold of
the characterizing relay
closure, %

3
100
30
Threshold for the characterizing relay
closure after overload triggered
opening
161
Characterizing relay
operation mode

0
4
0
0 - the relay is used as an alarm relay
1- the relay is used as a time relay
(closes after time specified in

pa-
rameter after load relay closure )
2-the relay is used for connecting addi-
tional load
3- the relay will close when load wat-
tless power threshold

is exceeded
4- relay will be switched on after ex-
ceeding of main tripping
162
Characterizing relay
activation mode when


0
2
0
0 – relay will close after expiration of
time

1 – relay will close after reduction of
consumed wattage to level 
163

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NOVATEK-ELECTRO ОМ-310
Settings and read-off
parameters
Code pa-
rameters
Minimum
values
Max.
values
Default
setting
Operation
Address
2 – relay will close after expiration of

time or after reduction of con-
sumed wattage to level of

whi-
chever is earlier
Delay of characterizing
relay closure relatively
to load relay closure

0
300
5
164
Allowable load wattless
power, kVar.

3
450
5
165
Current protection. Maximum current protection
Maximum current
protection type

0
5
0
0-protection with independent time de-
lay
Dependent time delay protection
types:
1-SIT; 2-VIT (LTI); 3-EIT; 4-UIT; 5-RI
166
Max
current
protection
tripping
setting
value,
ratio

0,8
9,0
2,0
ratio to the load rated current is as-
signed (functions at i
=
P = 0).
167
Current protection trip-
ping delay, sec

0,3
600
10,0
168
Protection function
permission

0
2
0
0- protection function prohibited
1- protection function permitted, after-
tripping automatic reset prohibited
2- protection function permitted, after-
tripping automatic reset permitted
169
Protection against line-to-earth fault (based on zero sequence current iF0)
Current fault tripping set-
ting, A

0,3
5,0
0,5
170
Protection
tripping
delay,s

0,3
2,0
1,0
171
Protection function
permission

0
2
0
0- protection function prohibited
1- protection function permitted, after-
tripping automatic reset prohibited
2- protection function permitted, after-
tripping automatic reset permitted
172
Voltage protection
Minimum line voltage, V

270
415
320
173
Min voltage de-energize
tripping delay time, sec

5
30
10
174
Minimum voltage pro-
tection function per-
mission

0
2
0
0- protection function prohibited
1- protection function permitted, after-
tripping automatic reset prohibited
2- protection function permitted, after-
tripping automatic reset permitted
175
Maximum line voltage, V

330
475
415
176
Max line voltage de-ener-
gize tripping delay time, s

1
10
2
177
Maximum voltage pro-
tection function per-
mission

0
1
0
0- protection function prohibited
1- protection function permitted, after-
tripping automatic reset prohibited
2- protection function permitted, after-
tripping automatic reset permitted
178
Line
voltage
imbalance,
V

15
120
35
179
Line voltage imbalance
de-
energize tripping delay
time, sec

1
30
5
180
Voltage imbalance pro-
tection function per-
mission

0
2
0
0- protection function prohibited
1- protection function permitted, after-
tripping automatic reset prohibited
2- protection function permitted, after-
tripping automatic reset permitted
181
Phase sequence pro-

0
2
0
0- protection function prohibited
182

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ОМ-310 NOVATEK-ELECTRO
Settings and read-off
parameters
Code pa-
rameters
Minimum
values
Max.
values
Default
setting
Operation
Address
tection function per-
mission
1- protection function permitted, after-
tripping automatic reset prohibited
2- protection function permitted, after-
tripping automatic reset permitted
Load Engagement and Automatic Reset Control
Automatic reset (AR)
time, sec

0
900
5
183
AR prohibited for all
faults (except voltage
faults)

0
1
1
0 - AR prohibited
1- AR permitted

parameter value is effective for all
types of faults except voltage faults.

,

,

parameters shallbeused
to
prohibit
AR in case of voltage
faults
184
Load relay operation
permitted after OM de-
vice power-on

0
2
1
0 – manual load start from OM-310
front panel
1- load start after AR delay time
load start after 2 sec delay
185
Load start/cutoff control
with use of OM-310
front panel

0
3
0
0 - prohibited
1- load energizing permitted
2- emergency load de-energizing per-
mitted
3- load energizing and de-energizing
permitted
See par. 2.4.9
186
Miscellaneous
Time within which av-
erage current value is
measured, sec

10
600
60
Time within which average current
value is measured (parameters iS1,
iS2, iS3 from Table 1.5)
187
Min number of setting
parameters mode ena-
ble

0
1
1
0-mode disabled
1- mode enabled
The mode change is enabled in the
service-engineer mode only.
188
Indication on OM-310
display panel before
load energize

0
2
1
0- line voltage Uab
1-active power PoA
2-AR time countdown
189
Parameter indication
mode

0
1
1
0-parameter value indicated continuously
1-parameter
value
indicated
within
15s
190
Complete equipment
operation time, days

0
999
0
when MODBUS/RS-232 interface data
transfer is utilized, the operation time
is transferred in hours
191
User access code

0
9
0
0 – keyboard unlocked
1-9 – user password
192
Service engineer
access code

000
999
123
000-access to service engineer level -
permitted
000-999 – service engineer password
193
System reset to factory
settings

0
1
0
After value 1 has been recorded and
parameter setup mode exited, the fac-
tory set parameters will be restored
194
(RS-485/ RS-232) serial interface parameters
OM-310 device commu-
nication address

1
247
1
195
Transfer rate

0
1
0
0: 9600 baud; 1: 19200 baud;
Transfer rate change will take effect af-
ter power-off/ and restarting power-on.
196
OM-310 response to
loss of connection

0
3
0
0-continue without warning
1- warning message, continue opera-
tion
2-warning message and load relay de-
energize, AR permitted after commu-
nication has been restored
3-warning message and load relay de-
197

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NOVATEK-ELECTRO ОМ-310
Settings and read-off
parameters
Code pa-
rameters
Minimum
values
Max.
values
Default
setting
Operation
Address
energize, AR prohibited after commu-
nication has been restored
Response timeout detec-
tion, sec

0
120
0
0 - prohibited
198
OM-310 communication
via serial channel permit-
ted

0
2
0
0- communication prohibited
1- communication via RS-232
2- communication via MODBUS
199
Device version

10
The parameter value depends on the
firmware version
200
Remotely controlled
load energizing and de-
energizing via RS-
232/RS485

0
2
0
0 – remote control prohibited
1- remote control permitted, load relay
closure permitted after ОМ-310 device
energizing
2- remote control permitted, load relay
closure prohibited after ОМ-310 power-
on until remote power-on command
has been issued
201
OM-310 Remote Opera-
tion control via remote
switch

0
4
0
0 – remote control via the switch
prohibited
1-4 see par 2.4.6
202
The starter functionality
monitoring (presence of
currents when load relay
is open)

0
1
0
0- off
1- on
203
* Note. The parameter is utilized if the characterizing relay functions in the additional load relay mode (2)
1.2.4 Operating controls and the dimensions of the ОМ-310 are shown in fig.1.1.
1 – red LED - SETUP glows when the relay is in parameter setup mode
2 – green LED - LOAD glows when the load relay is closed
3 – green LED - RELAY glows when the characterizing relay is closed
4 – green LED - MMSP (mode with minimal number of setting parameters) glows when the relay is in MMSP mode
5 - three-digit parameter mnemonic indication display:
-dot glows in the lower case of the display when ОМ-310 device is in service engineer access mode;
- dot glows in the middle case of the display line when a setup parameter value is secured by service engineer password;
- dot glows in the upper case of the display line when a setup parameter is not included in the MMSP list
6 - three-digit parameter value indication display
7 – blue LED -EXCHANGE glows during data exchange with PC
8 – red LED – FAULT:
- while load relay is open: the LED glows, when ОМ-310 is in fault mode (flickers, when AR after fault is possible);
- while load relay is closed, the LED flickers when the load consumed input power is over the main threshold, but the load
relay open time has not yet been reached
9 - plug connection for connecting ОМ-310 to PC via RS-232
10 – green LED - glows when the ОМ-310 characterizing relay works in the mode of controlling additional load (par. 2.4.3)
11 – green LED - TR glows when the ОМ-310 characterizing relay functions in the time relay mode and blinking when
OM-310 is working in signalization mode of main tripping exceeding of active power.

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ОМ-310 NOVATEK-ELECTRO
12 – button (marked in text as UP) – used to scroll through indicated parameters in the parameter view mode and
scroll through menus in the parameter setup mode
13 – button (marked in text as DOWN) – used to scroll through indicated parameters in the parameter view mode and
scroll through menus in the parameter setup mode
14 – key – RES/MEM/SEL – used to record parameters in setup mode; switch between groups of parameters displayed
in view mode, reset
15 - SETUP button engages the parameter setup mode
Figure 1.1 - OM-310 device controls and dimensions
N o t e 1 - In order to enhance the ОМ-310 reliability, for the mains voltage input, terminals with 7.5 mm spacing
were used. Standard contact numbering on the device case (5 mm) does not agree with such terminals, that is why
terminals in figure 2.1 are marked with intermediate values.
N o t e 2– LEDs 10 and 11 glow simultaneously when the ОМ-310 characterizing relay functions in the watl-
less power excess alarm mode
1.2.5 Power Limiting Functions
1.2.5.1 Assumptions utilized in power limiter function description:
a) voltage and current protections are off or corresponding parameters values are within permissible limits;
b) when energized, the load relay will close after AR time (=1 parameter);
c) time specified by t1n parameter exceeds the AR time ( parameter).
1.2.5.2 Limitation of active power if parameter  not equal 2 (under all relay activity conditions except of us-
ing it for connection of additional loading.
After ОМ-310 energizing, after AR time ( parameter) the load relay will close. If during operation the active
power consumed by the load crosses the main threshold for a time that is longer than assigned by “t1n” parameter,
the load relay will open. The load will be energized again after AR period, or after time specified by t1F parameter
(whichever is longer) (Figure 1.2).
The main threshold value and the power overload calculation depend on the “” parameter value.
When =0, the load consumed wattage is calculated for each phase separately and is compared with the
main threshold calculated as:
Main threshold (kW) = (“Pnn” * “P1F”) / (100*3), where
“Pnn” – cumulative rated load wattage, kW;
“P1F” – main threshold, %.
When=1, the cumulative load power input for all three phases is compared with the main threshold calcu-
lated as:
Main threshold (kW) = (“Pnn” * “P1F”) / 100, where
“Pnn” – cumulative rated load wattage, kW;
“P1F” – main threshold, %.
Simultaneously, the load input power is calculated for each phase separately and is compared with the second
threshold calculated as (threshold calculation for each phase + 20%):
The second threshold (kW) = (“Pnn” * “P1F” *1,2) / (100*3), where
“Pnn” – cumulative rated load wattage, kW;
“P1F” – main threshold, %.
Watt consumption crossing the first and the second thresholds is considered crossing the main threshold.
When =2, the cumulative load power input is compared with the main threshold calculated as:
Main threshold (kW) = (“Pnn” * “P1F”) / 100, where
“Pnn” – cumulative rated load wattage, kW;
“P1F” – main threshold, %.
Main threshold
Wattage
Load relay
Att – AR time
t1n - time, after which the load relay will open if the watts input crosses the main threshold

- 11 -
NOVATEK-ELECTRO ОМ-310
t1F - time, during which the load relay will be open after de-energizing resulting from the watts input crossing
the main threshold
Figure 1.2 - OM-310 operation in the power limiting mode when =0, =1, =3
1.2.5.3 Active power limiting during operation of a characterizing relay at = 2 ( relay used for connecting ad-
ditional load)
After ОМ-310 energizing, after AR time (Att parameter) the load relay will close. After the delay, defined by
“” or “” parameter (whichever time is longer), the characterizing relay closes while connecting additional load.
If during operation the active power consumed by the load crosses the additional threshold (line 2 figure 1.3) for a
time period that is longer than assigned by “” parameter, the characterizing relay will open.
Characterizing relay will re-close again:
а) at =0, after time, assigned by t2F parameter (instance of the characterizing relay closure - line “b” on
fig.1.3.);
b) at =1, when load consumed power will reduce till the additional load power-on threshold (line 3 on
fig.1.3) (the characterizing relay engaging point - line “a” on fig.1.3.);
c) at =2 depending on which event (a or b) comes first.
If during operation the active power consumed by the load crosses the additional threshold (line 1 figure 1.3) for
a time period that is longer than assigned by “” parameter, the characterizing relay and the load relay will open.
The load relay and characterizing relay will be re-closed after AR period, or after time specified by  parame-
ter (whichever of the time periods is longer) (Figure 1.3).
Load consumed input wattage
Characterizing relay in the mode of controlling
additional load
Load relay
1 – main threshold (“” parameter)
2 – additional de-energize threshold (“” parameter)
3 – additional energize threshold (“” parameter)
Figure 1.3 - OM-310 operation in the power limiting mode when =2
The wattages values for the main threshold, the additional threshold, and the additional load energize threshold
depend on the “” parameter value.
When =0, the load consumed power is calculated for each phase separately and is compared with the thre-
sholds calculated as:
Main threshold (kW) = (“Pnn” * “P1F”) /(100*3), where
“Pnn” – cumulative rated load wattage, kW;
“P1F” – main threshold, %.
Additional threshold (kW) = (“Pnn” * “P2F”) /( “100”*3), where
“P2F” – additional threshold, %.
When =1 the main threshold, the additional threshold and the energizing threshold are calculated similarly to
the way described under paragraph 1.2.5.2

- 12 -
ОМ-310 NOVATEK-ELECTRO
When =2, the thresholds values (kW) are defined as follows:
Main threshold (kW) = “Pnn” * “P1F” / “100”, where
“Pnn” – cumulative rated load wattage, kW;
“P1F” – main threshold, %.
Additional threshold (kW) = “Pnn” * “P2F” / “100”, where
“P2F” – additional threshold, %.
At any value of rPn, the additional load energizing threshold shall be determined as:
Energizing threshold (kW) = (“Pnn” * “P2n”) /(“100”), where
“P2F” – additional load energizing threshold, %.
1.2.6 Protection functions
1.2.6.1 Protection types
OM-310 device provides the following types of load protection:
- maximum phase current;
- against line-to-earth fault (based on zero sequence current):
- for minimum line voltage;
- for maximum line voltage;
- for line voltages imbalance (voltage negative sequence);
- for phase sequence order;
- starter unit operability control.
1.2.6.2 The overcurrent protection parameters are assigned relatively to the rated load current In (“” parame-
ter).
1.2.6.3 Overcurrent protection
The overcurrent protection is of three-phase type. It is engaged when at least one of the phase current values
reach the tripping threshold.
The protection has a time delay setting. The delay can be independent (constant), or dependent (SIT - reverse
dependent; VIT or LTI – very reverse dependent; EIT - extremely reverse dependent; UIT – ultra reverse depen-
dent; RI –type delay) - the tripping curves are displayed in Appendix 1.
When independent time delay protection is activated (fig. 1.4), the load relay is de-energized if one of the phas-
es current exceeds the threshold value within T period of time (parameter “” ).
Is = “” (tripping ratio) * In (load rated current), and T –
protection tripping delay time
Example. When = 4.0, In = 10,  = 10.0, the load
relay shall open in 10 sec after one of the phase currents crosses
40 A value.
Figure 1.4 - Principle of protection with an independent time delay
The operation of the dependent time delay protection (Fig. 1.5) conforms to IEC 60255-3 and BS 142 stan-
dards.
In corresponds to “ind” setting (rated current of
load); T (parameter “” – protection function time
constant) – corresponds to the trip delay time for 10 In.
To deal with very high amperage currents the
protection has a feature with an independent time delay:

- 13 -
NOVATEK-ELECTRO ОМ-310
Figure 1.5 - Principle of protection with dependent time delay
Graphs for the protection operation time constant equal to 1 sec (“” parameter) are provided in Appendix 1.
When a different value for time constant is set, the protection trip time changes proportionally to the time constant
(for example, at “”=10 seconds the protection trip time at the same current ratio will increase 10 times).
1.2.6.4 Ground fault protection:
- is activated when earth fault current reaches the trip threshold (“”);parameter);
- the load relay opens if the earth fault current crosses the trip threshold within T time period (“” parameter).
1.2.6.5 Voltage based protection
In voltage-based protections, before load energizing, OM -310 checks for corresponding threshold settings, and,
depending on their value, either permits or prohibits load energization; after load energization the voltage control is
retained.
Voltage-based protections include:
- protection for minimum line voltage (it trips when at least one of the line currents is less than the threshold set-
ting (“” parameter) within time specified by “” parameter);.
- protection for maximum line voltage (it trips when at least one of the line currents is greater than the threshold
setting (“” parameter) within time specified by “” parameter);
- protection for line voltages imbalance ( trips if difference between RMS line voltages exceeds the set threshold
(“” parameter) within time assigned by “” parameter).
1.2.6.6 Protection based on phase sequence order trips in case of phase sequence order fault or phase coin-
cidence it opens the load relay and locks its further operation.
1.2.6.7 Starter unit operability control (at =1). If currrents are present when the relay is open, the starter is
considered faulty. Further OM-310 operation is locked. The alarm reset can be performed by de-energizing only.
1.3 PRODUCT PACKAGE CONTENTS
The product package contents are shown in Table 1.7.
Table 1.7 - Product package contents
Description
Abbreviation
ОМ-310
ОМ-310
Differential current transformer (zero sequence transformer)*
Cable for communication with PC via RS-232*
KC-01
Transmitter cable for communication with PC via USB*
KC-USB-01
* - supplied optionally
1.4 EQUIPMENT FEATURES AND OPERATION
ОМ-310 is a microprocessor-based digital device that provides a high degree of reliability and accuracy. The
device doesn't need any auxiliary supply: it's self-powered by the voltage to be monitored.
ОМ-310 device is equipped with three built-in CTs, through which power phase mains are conducted.
2. INTENDED USE
2.1. SAFETY
All connections must be performed on dead device.
2.2 ОМ-310 DEVICE CONTROL
2.2.1 Control Modes
OM-310 has five control modes:
-keyboard lock level;
- mode with minimal number of setting parameters (further on referred to as MMSP);
-user level;
-service engineer level;
- remote control.
In all operation modes the following features are available:
- viewing measured and displayed parameters (Tablе 1.4). Scrolling through parameters list is performed by
DOWN and UP buttons;
-faults log view (п.2.4.8).

- 14 -
ОМ-310 NOVATEK-ELECTRO
2.2.2 Disabled keypad mode
When keypad is locked, viewing and resetting programmable parameters is not possible.
When keypad is locked, pushing SETUP button will result in LOC message display. To unlock the keyboard the
SETUP button shall be pressed again. The "SETUP" LED lights up, and figure "0" is blinking on the indicator. With
the UP and DOWN buttons user enters a password digit from 1 to 9 and presses the RECORD/RESET/SELECT
button. If the password is correct, the keypad will be unlocked. If after the keypad was unlocked no button is
pressed during 15 sec and the lockage setting is not released by user, the keypad will relock.
The unblocked keypad allows:
-to operate in MMSP mode;
-to change and to view the user level parameters;
-to view the service engineer level parameters.
2.2.3 MMSP – mode with minimum number of setting parameters
MMSP is devised to ease the service personnel’s operations with ОМ-310.
To employ MMSP mode in OM-310, the user needs to set =1 parameter, or perform resetting to factory set-
tings. (2.2.4). When ОМ-310 unit is in this operation mode, green LED “MMSP”is on.
In MMSP for normal activity of OM-310 is enough fix parameter  (nominal active power table 1.5 if necessary
parameters  (time where through loading relay will be switched OFF after of energy input exceedence of main
thresholds table 1.5) and  (time interval of cut off loading relay on energy input exceedence of main threshold
table 1.5)
On duty of external TT is necessary to fix following parameters:
-type of TT (parameter , table 1.5) external;
-nominal current of TT (parameter , table1.5).
The difference between MMSP mode and the user mode is that the parameters not included in the MMSP regis-
ter are set to default factory values.
ATTENTION! If some programmable parameters have been modified by the user or service engineer, but
not included in the MMSP register, switching to MMSP mode will reset such parameters to factory settings.
The parameters included in this register cannot be viewed or modified. Operations with the MMSP register pa-
rameters are similar to the user level operations.
Adding parameters to the MMSP register and MMSP mode disabling is possible only in service engineer
access mode.
When switching off the MMSP mode (setting parameter =0) LED “MMSP” goes off. In the user mode all
parameters list is displayed, but to change a parameter, parform the following:
- with DOWN and UP buttons choose the parameter to be added;
- push buttons DOWN and UP simultaneously.
2.2.4 User level
To view and to change the user level parameters one needs to press the SETUP button, then "SETUP" LED will
glow. Scroll parameters with DOWN and UP buttons, enter parameter change mode – repeat push SETUP button
(the parameter value starts to flicker), change parameters – with DOWN and UP buttons, record parameter -
RECORD/RESET/SELECT , to return to menu without change – press SETUP button again. If no button is pressed
during 15 sec the ОМ-310 will transfer to the initial state.
If a parameter change is forbidden (a dot in the middle digit field of the parameter mnemonic indicator glows),
then the parameter change is possible only in Service Engineer level after the prohibition has been released.
2.2.5 Service Engineer Level
Access to the Service Engineer level.
Push SETUP button and hold for 5 sec. If the level is protected by a password, the label PAS appears on the
indicator. The "SETUP" LED lights up, and indication "000" flickers on the parameter value indicator. With the UP
and DOWN buttons enter the three-digit service engineer password, digits from 1 to 9 and separate dialing with
pressing the RECORD/RESET/SELECT button. If the password is incorrect, the PAS label lights on blinking in the
higher position of the value indicator, and ОМ-310 goes back to the initial state after 15 sec, otherwise the first pa-
rameter of the service engineer menu appears on the indicator.
Scroll parameters with DOWN and UP buttons, enter parameter change mode – repeat push SETUP button (the
parameter value starts to flicker), change parameters – with DOWN and UP buttons, record parameter -
RECORD/RESET/SELECT , to return to menu without change – press SETUP button again. If no button is pressed
during 15 sec the ОМ-310 will transfer to the initial state.
While ОМ-310 is in Service Engineer mode, the decimal point in the lower digit position of the mnemonic indica-
tor is on.
In the Service Engineer level the access to any user level parameter can be prohibited or permitted by simulta-
neous the SET and DOWN buttons pressing. Access denial is indicated by decimal point in the middle digit position
of the mnemonic indicator.

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NOVATEK-ELECTRO ОМ-310
While in Service Engineer access mode, any additional parameter can be added to the MMSP parameter regis-
ter. Action:
- with DOWN and UP buttons choose the parameter to be added;
- push buttons DOWN and UP simultaneously.
To exclude a parameter from the MMSP register:
- with DOWN and UP buttons choose the parameter to be excluded;
- push buttons DOWN and UP simultaneously.
When a parameter is excluded form the MMSP mode register, a decimal point glows in the higher digit position
of the mnemonic indicator.
2.2.6 Restoring factory settings.
There are two ways to restore the factory settings.
Way 1. Set up parameter =1. Upon exit from the parameter setup mode all factory settings will be restored
(except the Service Engineer Password).
Way 2. When powering ОМ-310 on, hold down SETUP and RES/MEM/SEL buttons for 2 seconds. All factory
settings including the Service Engineer will be restored (Service Engineer password – 123).
After completion of the factory settings setup, ОМ-310 will start operation in MMSP mode, which includes the
following parameters:
- CT type (external or integral);;
- CT rated current (set in case of external CT); ;
- rated power of load, .
2.3 OM-310 PRE-OPERATION PROCEDURE
2.3.1 When operating with load power ranging from 3 kW to 30 kW, use of built-in current transformers is al-
lowed. The mains leading to the load must be conducted through openings in ОМ-310 casing (each phase wire
uses a separate opening).
When using other capacity loads, current transformers with 5A rated output current shall be connected in accor-
dance with Fig 2.1. For correct OM-310 operation, the current transformers’ polarity must be observed.
2.3.2 Run all three power phase cables through differential current transformer (zero sequence transformer)
and connect the DCT to ОМ-310.
2.3.3 Connect ОМ-310 to power mains in accordance with figure 2.1.
2.3.4 To operate ОМ-310 via PC as control or monitoring device with use of “ОМ-310 Control Panel” software:
- install “ОМ-310 Control Panel” software to your PC by running setup_UBZ314.msi application;
-connect “ЭВМ” (PC) connection plug on ОМ-310 front panel to RS-232 plug on PC with use of KC-01 cable
or to USB jack of PC via KC-USB-01 cable;
-set parameter “=1”.
N o t e 1- “setup_ UBZ-ОМ.msi” software can be downloaded from Novatek-Electro website
(http://www.novatek-electro.com/production_ubz.htm).
N o t e 2 - КС-01, KC-USB-01 cables are optional and can be ordered separately. Users can make KC-01 cable
themselves following the diagram shown in Fig. 2.2.
N o t e 3 -Custom-developed software can also be used to operate ОМ-310 .
2.3.6 When using MODBUS, connect communication lines to terminals 33, 34, 35 of. Set “=2” parameter.
2.3.7 Energize ОМ-310.
N o t e - ОМ-310 is supplied with rated load power set equal to zero. In this case the ОМ-310 load relay
will not close before the rated load power is set up.
Load relay closing sequence is controlled by  и (par. 2.4.1.) parameter values.
2.3.8 Set up required parameter values in the menu.
2.3.9 De-energize ОМ-310.
2.3.10 Connect the load magnetic contactor (further referred to as MC) according to Fig 2.1.
N o t e - When the load relay is energized, contacts 5-6 and 8-9 are closed, when the relay is de-energized,
contacts 4-5 and 7-8 are closed.

- 16 -
ОМ-310 NOVATEK-ELECTRO
4
L2_OUT2
31.5
51
T3
26
N
T1b
K1-1-nc
T1e
8
6
L1
1
Designation
K1-2-nc
GND_RS232
L1_OUT2
23
TxD_rs232
L3
T3b
K1-1-com
33
АВ
Cont
OM-310
K1-1-no
16
T1
K2-com
30
27
L2
18
T3e
3
25
Cont
cont
15
K1-1
S1
A RS-485
T2
Designation
GND
MS1
T2e
N
K1-2-no
34
Tdif_e
7
K2-no
9
28.5
X1-2
4
X2
K1-2
K2-nc
5
MS2
X1-1
K2
L1_OUT1
T4
Designation
L1
B RS-485
24
17
Cont
L3_OUT2
2
K1-2-com
T2b
Tdif_b
L3_OUT1
14
2
L2
RxD_rs232
19
L2_OUT1
35
52
3
GND
L3
S1 – remote switch
АS – automatic switch
MС1 –additional load magnetic contactor
MС2 – main load magnetic contactor
K1 relay –load relay
K2 relay –characterizing relay
Т1-Т3 –external CTs
Т4 – differential current transformer.
Figure 2.1 -ОМ-310 connection schematic with use of external CTs and at =2
(characterizing relay operation in the mode of controlling additional load)
2.4 INTENDED USE
Note: In the ОМ-310 operation description, it is assumed that the protections described are enabled and all
necessary sensors are connected.
2.4.1 ОМ-310 operation before load relay closure
2.4.1.1. ОМ-310 operation after power-on (first start)
After power-on, the mnemonic indicator displays  for 1-2 seconds, and then before load energizing ОМ-310
tests:
- mains voltage quality: whether voltage is present on all three phases, if the mains voltage is symmetrical,
what the RMS line voltage value is;
-correct phase sequence, absence of phase fritting.
When any of inhibiting factors is present, the load relay is not closed, and on the mnemonics indicator FAULT
LED glows.
Depending on the SiP parameter, the indicator displays:
- line voltage Uab at =0;
- active power (PoA) at =1;
- AR time countdown in seconds, (Att) while =2.

- 17 -
NOVATEK-ELECTRO ОМ-310
When power-on inhibiting factors are not present, the load relay closure is defined by APd parameter value
(ОМ-310 device operation after power-on) At =0 the load relay will not close.To close load relay in this
case both DOWN and UP buttons have to be pressed simultaneously.
1) When =1 the load relay will close after AR time.
2) When =2 the load relay will close in 2 sec after power-on.
Simultaneously with the load relay closure, green LED LOAD starts to glow.
ОМ-310 operation with remote control permitted via RS-232/RS-485 (=1, =2) is covered in paragraph 2.4.5.
ОМ-310 operation with remote control permitted via switch (c=1, c=2) is covered in paragraph 2.4.6.
2.4.1.2. ОМ-310 operation after a fault-caused de-energizing
The ОМ-310 device operation in such case is similar to the first start operation , but the load relay closure is not
dependent on the  parameter value.
If after a fault AR is prohibited (“=0”), the load power-on is not possible before ОМ-310 de-energizing.
parameter value is effective for all types of faults except voltage faults. , = ,parameters shall be
used to prohibit AR in case of voltage faults.
2.4.1.3. ОМ-310 operation after de-energizing tripping caused by excceding the watt input
ОМ-310 operation in this case is covered under par. 1.2.5.
2.4.2 OM-310 operation before load relay closure
After load relay closure ОМ-310 performs the following:
- control and limiting the active and wattles power by input load wattage (1.2.5);
- current overload protection (1.2.6.3);
- protection against line-to-earth fault (1.2.6.4);
- voltage protection (maximum, minimum, phase imbalance) (1.2.6.5);
- starter unit operability control (1.2.6.6).
The indicator can display either phase A current or a user-selected parameter value. The value of the user-
selected parameter can be displayed either constantly (=0), or within 15 sec, and then phase A current (=1)
indication is displayed again.
2.4.3 Characterizing relay operation
Functions performed by the characterizing relay are defined by  parameter.
When  =0, the relay functions as signaling alarm relay ( and TR LEDs are off). The relay contacts are
closed in case of any fault specified in Table 2.7.
When  =1, the relay functions as time relay (TR LED glows): the relay closes upon expiration of time set by
“” parameter, after load relay closing.
When  = 2, the relay is used to control switching additional load ( LED glows) (1.2.5.3).
When =3 we use relay for exceedence signalization of reactive power (LEDs and TR are )
Functional relay is switched ON by exceedence of total reactive power across tree phases – (admissible
reactive power of loading) and switched OFF if not exceedence.
When =4 we use relay for exceedence signalization of reactive power main threshold (LED is blinking)
(p.1.2.5.4.) The threshold value is being calculated according p.1.2.5.2.
N o t e -When the characterizing relay is closed, contacts 1-2 are open, and contacts 2-3 are closed.
2.4.4 Work with RS-232/RS-485 interface under MODBUS protocol in RTU mode.
The OM allows for data exchange with an external device via serial interface under MODBUS protocol. During
data exchange via RS-485 or RS-232 blue LED “EXCHANGE” glows.
2.4.4.1 Communication parameters:
- device address: 1-247 (parameter);
- data transfer rate: 9600 baud, 19200 baud ( parameter);
- response to loss of carrier: warning and continue operation, warning and load de-energizing, continue opera-
tion without warning ( parameter);
- response timeout detection: 1sec –120sec (  parameter);
- transmission word format – 8 bit, no parity check, two stop bits.
2.4.4.2 ОМ-310 control from PC
Communication between PC and ОМ-310 is effected through serial interface. The connection schematic is
shown in fig. 2.2. Each ОМ-310 has a unique communication address. PC controls each OM recognizing them by
their address.
OM-310 can operate within RTU mode controlled Modbus networks.

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ОМ-310 NOVATEK-ELECTRO
Figure 2.2 - ОМ-310 connection to PC schematic
2.4.4.3. Communication protocol
The exchange between PC and ОМ-310 is effected via data packages. Data packet format is given in Table 2.1.
Table 2.1
START
silence interval – over 2msec at 9600 baud transfer rate, or over 4 msec at 19200 baud
transfer rate
ADR
ОМ-310 communication address (8 bit)
CMD
Command code 8 bit
DATA 0
Data contents:
N*8 data bit (n<=24)
….
DATA (n-1)
CRC CHK low
CRC checksum
16 bit
CRC CHK high
END
silence interval – over 2msec at 9600 baud transfer rate, or over 4 msec at 19200 baud
transfer rate
2.4.4.4 CMD (command code) and DATA (data symbols)
Data symbols format depends on command codes.
Command code –0x03, n-words read.
For example, read 2 continuous words swapped from 2102H in ОМ-310 initial address with 01H communication
address (Table 2.2)
Table 2.2
Command message
Response message
ADR
0x01
ADR
0x01
CMD
0x03
CMD
0x03
Start data address
0x21
0x02
Data amount, bytes
0x04
Data amount in words
0x00
0x02
Data contents by address
0x17
0x70
CRC CHK low
0x6F
Data contents by address
0x00
0x00
CRC CHK high
0xF7
CRC CHK low
0xFE
CRC CHK high
0x5C
Command code 0x06, record – one word
Using this command is not recommended as recording incorrest data may lead to ОМ-310 failure.
Data recording is possible only to the programmable parameters addresses (Table 1.5), except for parameters
listed in Table 2.3.

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NOVATEK-ELECTRO ОМ-310
Table 2.3
Settings and read-off parameters
Code parameters
Address
Equipment operation time counter, days

207
User access code

208
Service engineer access code

209
System reset to factory settings

210
Device version

217
A parameter recording is performed independently from the installed Service Engineer protection (the entry
made via communication line has a higher priority).
When a new parameter value is recorded into a MMSP- protected cell, such parameter will automatically be ex-
cluded from this mode.
Recorded parameters must be aliquot to iteration specified in Table 1.5.
For example, record 1000 (0x03E8) to register with 0x00A0 address into ОМ-310 with 01H communication ad-
dress.
Table 2.4
Command message
Response message
ADR
0x01
ADR
0x01
CMD
0x06
CMD
0x06
Start data address
0x00
0xA0
Start data address
0x00
0xA0
Data
0x03
0xE8
Data
0x03
0xE8
CRC CHK low
0x89
CRC CHK low
0x89
CRC CHK high
0x56
CRC CHK high
0x56
Command code 08h – diagnostics.
08h function provides a number of tests for checking communication system between PC and OM-310, and for
OM-310 integrity control.
The function uses the sub function field to specify the action performed (test).
Sub function 00h – query data return.
Data transferred in the query field must return in the response data field.
Request and response example is given in Fig. 2.3.
Figure 2.3 - Example of sub function request and return 00h – data request return.
01h sub function – communication options restart
ОМ-310 peripheral port shall be initialized and restarted.
Request and response example is given in Fig. 2.4.
Figure 2.4 - Example of sub function request and return 01h – communication options restart.
2.4.4.5 CRC - Cyclic redundancy check code
The checksum (CRC16) is a cyclic redundancy check code based on A001h polynomial. The transmitting de-
vice forms the checksum for all bytes of the message transmitted. The receiving device similarly forms the check-
sum for all bytes of the message received, and compares it to the checksum received form the transmission device.
When received and transmitted checksums do not match, an error message is generated.

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ОМ-310 NOVATEK-ELECTRO
The checksum field size occupies two bytes. The checksum within message is transferred with low byte coming
first.
The checksum is registered under the following algorithm:
1) load CRC register (16 bit) with units (FFFFh);
2) exclusive OR with first 8 bytes of message and CRC register contents;
3) offset the result one bit to the right;
4) if the offset bit =1, the exclusive OR of the register contents with A001h value;
5) if the offset bit=0, repeat step 3;
6) repeat steps 3, 4, 5 until 8 offsets have been completed;
7) exclusive OR with the next 8 bits of the message byte and CRC register contents;
8) repeat steps 3 – 7, until all bytes of the message have been processed;
9) the finite register contents will contain the checksum.
Here is an example of CRC code generation with use of C programming language. The function takes two ar-
guments:
Unsigned char* data <- a pointer to the message buffer
Unsigned char length <- the quantity of bytes in the message buffer
The function returns the CRC value as a type of unsigned integer.
Unsigned int crc_chk(unsigned char* data, unsigned char length)
{int j;
unsigned int reg_crc=0xFFFF;
while(length--)
{
reg_crc ^= *data++;
for(j=0;j<8;j++)
{
if(reg_crc & 0х01) reg_crc=(reg_crc>>1) ^ 0xA001; // LSB(b0)=1
else reg_crc=reg_crc>>1;
}
}
return reg_crc;
}
2.4.4.6 Register addresses
The register addresses of the measured and calculated parameters of the ОМ-310 device are given in table
1.4. The addresses of the programmable parameters are given in table 1.5.
Additional registers and their functions are shown below in table 2.5.
Table 2.5
Description
Address
Application
Comment
OM status register
240
Bit 0
0-no fault
1- fault (fault code in register 241)
Bit 1
0- load relay open
1- load relay closed
Bit 2
0- characterizing relay open
1- characterizing relay closed
Bit 3
0 – restart not activated
1- AR expected
Bit 5-4
Characterizing relay operation mode
00 – alarm relay
01 – time relay
10 – additional load
11 – alarm relay for wattles power excess
Bit 6
0- MMSP mode disabled
1- MMSP mode enabled
Fault register 1
241
bit mapping shown in table 2.8
0-no fault
1-fault
Fault register 2
242
bit mapping shown in table 2.8
Fault log
Fault code 1
243
fault code according to table 2.8
value of parameter 1
244
parameter value according to table 2.8
Fault time 1
245
two upper bytes
246
two lower bytes