ABB OTM C 21D User manual

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INSTALLATION AND OPERATING INSTRUCTION
Automatic Transfer Switch
OTM_C_21D
— Automatic Transfer switch 34OTM_C_21D rev. E / 1SCC303015M0201 / EN

2AUTOMATIC TRANSFER SWITCH, OTM_C_21D
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Table of contents
1. SYMBOLS & TERMS 3
2. PRODUCT OVERVIEW 4
3. QUICK START 78
4. INTERFACE AND SETTINGS 17
5. TECHNICAL DATA 22
6. INSTALLATION 23
7. OPTIONAL ACCESSORIES 26
8. MAINTENANCE AND COMMON
TROUBLESHOOTING 29
9. APPENDIX 30

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AUTOMATIC TRANSFER SWITCH, OTM_C_21D
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1. Symbols & Terms
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1.1 Use of symbols
Risk of Electric shock: warns about a situation where a hazardous voltage may cause phys-
ical injury to a person or damage to equipment.
General warning: warns about a situation where something other than electrical equip-
ment may cause physical injury to a person or damage to equipment.
Caution: provides important information or warns about a situation that may have a detri-
mental effect on equipment.
Information: provides important information about the equipment.
Table 1. Explanations of abbreviations and terms
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1.2 Explanations of abreviations and terms
OTM_C21D Automatic transfer switch, the type name
LN1-Switch I Power supply line, e.g. the primary line
LN2-Switch II Power supply line, e.g. the secondary line used in emergency cases
EMRG OFF Used to drive the automatic transfer switch transfers to the “O” position when
receiving EMRG OFF signal.
AUTO Automatic mode
Remote test A sequence to test the functionality of the automatic transfer switch
Ts Transfer delay
TBs Return delay
OV Adjustable overvoltage threshold
UV Adjustable undervoltage threshold

4AUTOMATIC TRANSFER SWITCH, OTM_C_21D
The OTM_C21D automatic transfer switch can be
used as a source transfer switch in a three-phase
or single-phase networks. Monitored conditions
are, no-voltage, phase-loss, overvoltage and un-
dervoltage detection, transfer delays, generator
start and stop, and remote test function. Source
transfer can be performed using a manually
The standard package includes:
1. automatic transfer switch, 2. handle, 3. handle storage clip 4. terminal plug, 5. mounting kit
Figure 1. OTM_C_21D automatic transfer switch
1. Handle for manual operation
2. Place for auxiliary contact blocks
3. Push button
4. Mimic panel
5. Voltage sensing connections
6. Locking clip for padlock
7. Locking latch for releasing the handle and
locking electrical control
8. Locking clip for locking manual operation
9. Dip switches
10. Rotary switches
11. Connecting terminal
12. Modbus RTU access
10 4 5
7
11
9
8 1 3 6 2
12
operated handle, locally using push buttons or
fully automatically. The automatic mode includes
several operating methods: Line 1 priority, no line
priority and manual back switching mode. OTM_
C21D can achieve communication function by
using the optional external Modbus RTU module.
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2. Product overview
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2.1 Product overview and packing

5
AUTOMATIC TRANSFER SWITCH, OTM_C_21D
And the return sequence can be summarized in
the following steps:
•The Line 1 will start the normal functioning
•Return delay TBs
•Change-over switch (Switch II) to the position 0
•Change-over switch (Switch I) to the position I
•Generator stop delay Gs
•Generator stop
Figure 2. Automatic Switching Sequences in OTM_C_21D, Line 1 priority
The transfer sequence of OTM_C21D can be sum-
marized in following steps:
•An anomaly occurs on the Line 1 (LN1)
•Generator start, immediately start generator in
case of black-out, phase-loss, overvoltage or
undervoltage (If Generator mode is selected)
•The Line 2 start the normal functioning,
transfer delay Ts
•Change-over switch (Switch I) to the position 0
•Change-over switch (Switch II) to the position II
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2.2 OTM_C21D switching sequence
2.2.1 Line 1 Priority (default mode)

6AUTOMATIC TRANSFER SWITCH, OTM_C_21D
The transfer sequence of OTM_C21D can be sum-
marized in following steps:
•An anomaly occurs on the Line 1 (LN1)
•Transfer delay Ts, in case of black-out, phase-
loss, overvoltage and undervoltage conditions
•Change-over switch (Switch I) to the position 0
•Change-over switch (Switch II) to the position II
And the return sequence can be summarized in
the following steps:
•The Line 1 will start the normal functioning
•Change-over switch stays in position II
•An anomaly occurs on the Line 2 (LN2)
•Return delay TBs
•Change-over switch (Switch II) to the
position 0
•Change-over switch (Switch I) to the position I
Figure 3. Automatic Switching Sequences in OTM_C_21D, No line priority
Generator can not be used in no line priority. Keep Dip switch “GEN SEL” setting “0”
in this mode.
2.2.2 No line priority

7
AUTOMATIC TRANSFER SWITCH, OTM_C_21D
The transfer sequence of OTM_C21D can be sum-
marized in following steps:
•An anomaly occurs on the Line 1 (LN1)
•Generator start, immediately start generator
in case of black-out, phase-loss, overvoltage or
undervoltage (If Generator mode is selected)
•The Line 2 start the normal functioning,
transfer delay Ts
•Change-over switch (Switch I) to the position 0
•Change-over switch (Switch II) to the
position II
Figure 4. Automatic Switching Sequences in OTM_C_21D, Manual return mode
And the return sequence can be summarized in
the following steps:
•The Line 1 will start the normal functioning
•Change-over switch stays in position II
•An anomaly occurs on the Line 2 (LN2)
•Change-over switch stays in position II
•Change-over switch can be transferred
manually back to position I
2.2.3 Manual return mode

8AUTOMATIC TRANSFER SWITCH, OTM_C_21D
To operate the switch manually:
1.Attach the handle to the switch panel. You can
attach the handle in any position.
2.When the handle is attached, the automatic
transfer switch will automatically be in Manual
mode and won’t operate automatically in case
of line failure. The AUTO LED on the mimic panel
is OFF.
Figure 5. Operating the switch manually
When the handle is inserted into the switch, the switch will enter “manual mode” with the
automatic operation disabled.
Do not adjust wires when the transfer switch is being energized.
Before the power-on operation of the transfer switch, please operate the switch manually
to confirm it is in normal function.
With the power supply function in “normal” and without the handle inserted and EMRG OFF
signals, the initially energized switch will enter automatic mode and transfer to the main
line. Keep the handle inserted if you do not want the switch to be in automatic mode upon
initial energization.
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3. Quick start
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3.1 Operating the switch manually (local operation)

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AUTOMATIC TRANSFER SWITCH, OTM_C_21D
OTM_C21D must be in automatic mode and the
“AUTO” LED is on in order that the switch can
perform automatic transfer cycles according to
the pre-set operating mode.
To operate the switch electrically:
•If the handle inserted
1. Press handle locking clip and remove the handle
from the switch.
2. Press “AUTO” button and the “AUTO” LED will
be ON, indicating automatic mode.
Figure 6. Selecting the automatic transfer OTM_C_21D, switch to Auto Mode
2
1
3
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3.2 Automatic operation
•If handle is not inserted
1. If “AUTO” LED blinks, press “AUTO” button and
the “AUTO” LED will be ON, indicating auto-
matic mode.
2. Automatic operation includes three operating
modes: Line 1 priority (factory default setting),
No line priority, and manual return mode.

10 AUTOMATIC TRANSFER SWITCH, OTM_C_21D
Figure 7. Remote test connection in OTM_C_21D
In the test sequence, the main power supply circuit will be closed.
If the test sequence is interrupted due to power failure, the automatic transfer switch will
enter “automatic mode” after power recovery.
In automatic mode, “AUTO” LED is ON and you can
transfer the switch using I, O, and II push buttons
on the front panel of the switch.
Press “AUTO” button to return the automatic
operation.
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3.3 System testing
3.3.1 Local test
The procedure of the remote test is as follows:
1. Connect to the remote test signal according to
Figure 7.
2. Ensure that the OTM_C21D is in automatic
mode (“AUTO” LED is on).
3. Short circuit the remote test signal for at least
100 ms until the “AUTO” LED blinks to enter the
test mode. Under test mode, the automatic
transfer switch will simulate switching cycle
and finally return to its original position prior
to the activation of the test mode.
e.g., when the switch is in Position I:
Enter test signals; the switch transfers to
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Position I. Entering test signals is invalid before
the automatic transfer switch returns to its
original position.
Under test mode, press the “AUTO” button to
cancel test mode and return to automatic
mode. The “Auto” LED will be “ON” as normal.
4. After the remote test finishes, the OTM_C21D
automatically returns to the automatic mode
(“AUTO” LED is on).
3.3.2 Remote test

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AUTOMATIC TRANSFER SWITCH, OTM_C_21D
Figure 8. Locking the electrical operation
Ø5-6 mm
By default, the manual operation can
only be locked in position 0. The
handle can be padlocked by pulling
out the clip from the handle and
place the padlock on the handle see
Figure 9.
1
2
3
4
Ø5-6 mm
The switch can be padlocked in any position,
causing that all operating modes and test
operations are disabled, and handle cannot be
inserted. See below for operation:
Figure 9. Locking the manual operation
3.4.1 Locking the electrical operation
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3.4 Locking
3.4.2. Locking the manual operation

12 AUTOMATIC TRANSFER SWITCH, OTM_C_21D
OTM_C21D can achieve communication function
by using the optional external Modbus RTU
module.
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3.5 Modbus communication function
Figure 10. Modbus RTU communication module
3.5.1 Modbus parameters
Parameter Value
Modbus Address 1…32 (Default 1)
Modbus Baud Rate 4800bps
9600bps (Default)
19200bps
38400bps
Modbus Stop Bits 1 Stop Bit (Default)
2 Stop Bits
Modbus Parity None
Odd
Even (Default)
Local/Remote Local monitoring mode (Default)
Remote control mode
Table 2. Modbus parameters of OTM_C21D
3.5.2 Modbus functional code
Function code Name
03(0x03) Read Holding Registers
04(0x04) Read Input Registers
06(0x06) Write Single Register
16(0x10) Write Multiple Registers
17(0x11) Report Slave ID
Table 3. Modbus functional code

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AUTOMATIC TRANSFER SWITCH, OTM_C_21D
3.5.3 OTM_C21D registers information
Register Address
(DEC)
Function
code
(DEC)
Values
SWITCH I_STATUS 1 04 0=Open
1=Closed
SWITCH II_STATUS 2 04 0=Open
1=Closed
LN1_U1 VOLTAGE 3 04 Phase voltage for 2P/4P
Line Voltage for 3P
Voltage at 1V accuracy
(e.g. 230=230V)
LN1_U2 VOLTAGE 4 04
LN1_U3 VOLTAGE 5 04
LN2_U1 VOLTAGE 6 04
LN2_U2 VOLTAGE 7 04
LN2_U3 VOLTAGE 8 04
LN1_LINE_STATUS 9 04 0= Voltage OK
1= No voltage
2= Undervoltage
3= Overvoltage
4= Phase missing
LN2_LINE_STATUS 10 04 0= Voltage OK
1= No voltage
2= Undervoltage
3= Overvoltage
4= Phase missing
RATED_VOLTAGE 11 04 0=220/380V
1=230/400V
2=240/415V
UNDERVOLTAGE_THRESHOLD 12 04 5,10,15,20,25,30 %
OVERVOLTAGE_THRESHOLD 13 04 5,10,15,20,25,30 %
TRANSFER_DELAY_TS 14 04 0,1,2,3,5,10,15,20,25,30 s
RETURN_DELAY_TBS 15 04 0,5,10,20,30,60,120,300,600,900 s
Information of registers, values and access is
available in following table
Continued on next page

14 AUTOMATIC TRANSFER SWITCH, OTM_C_21D
Register (continued) Address
(DEC)
Function
code
(DEC)
Values
MODBUS ADDRESS 16 03/06/16 1…32
MODBUS BAUD_RATE 17 03/06/16 0=4800
1=9600
2=19200
3= 38400
MODBUS PARITY_CHECK 18 03/06/16 0=No parity
1=Odd parity
2=Even parity
MODBUS STOP_BIT 19 03/06/16 0=1 Stop bit
1=2 Stop bit
DEVICE_WORKING_MODE 20 04 0=Manual switching mode
1=Emergency off mode
2=Local test mode (see 3.3.1)
3=Remote test mode (see 3.3.2)
4=Auto mode
LINE_PRIORITY 21 04 0=Line 1 priority
1=No line priority
2=Manual back switching
EMERGENCY_OFF_STATUS 22 04 0=Emergency off not happen or elimi-
nated
1=Emergency off happens
OPERATION_COUNTER 23 04 Number of switch position transitions
PRESENT_ALARM 24 04 0=No alarms
1= Switch I transfer fail
2= Switch II transfer fail
3=Both I and II are ON
4= Switch I transfer fail in emergency off
5= Switch II transfer fail in emergency off
Continued on next page

15
AUTOMATIC TRANSFER SWITCH, OTM_C_21D
Register (continued) Address
(DEC)
Function
code
(DEC)
Values
LAST_ALARM 25 04 0=No alarms
1= Switch I transfer fail
2= Switch II transfer fail
3=Both I and II are ON
4= Switch I transfer fail in emergency off
5= Switch II transfer fail in emergency off
SW_VERSION 26 04 Bit8-15= Major SW version (e.g. 0x1A=26)
Bit0-7 =Minor SW version (e.g. 0xAA=170)
PHASES 27 04 0= 3 phases with Neutral line
1= 3 phases without Neutral line
2= 1 phase
RATED_FREQUENCY 28 04 0=50Hz
1=60Hz
GENERATOR_STOP_DELAY 29 04 0=30s
1=240s
GENERATOR_USAGE 30 04 0= No Generator
1= Generator In Use
GENERATOR_START 31 06 1=Start generator
CONTROL 32 06 1= Remote control to I
2= Remote control to O
3= Remote control to II
4= Enter remote test function (see 3.3.2)
OPERATING_MODE 33 03/06 0=Local monitoring mode
1= Remote control mode
Table 4. OTM_C21D register information
Modbus parameters configuring and ATS control function is available only when OTM_C21D
is working in remote control mode
Remote control can only be operated under automatic operation mode
After remote control, OTM_C21D must be reset to Local monitoring mode, then it can re-
turn to automatic operation mode

16 AUTOMATIC TRANSFER SWITCH, OTM_C_21D
3.5.4 Cyber security
Disclaimer It is the sole responsibility of the customer to provide and continuously ensure a
secure connection between the product and the customer network or any other
network. The customer is required to establish and maintain any appropriate
measures (including but not limited to the installation of firewalls, application of
authentication measures, encryption of data, installation of anti- virus programs,
etc.) to protect the product, the network, its system and the interface against any
kind of security breach, unauthorized access, interference, intrusion, leakage and/
or theft of data or information. ABB and its affiliates are not liable for damage
and/or losses related to such security breaches, unauthorized access, interferen-
ce, intrusion, leakage and/or theft of data or information.
Secure
Deployment
The user of the product should be aware that the unsecure nature of the serial
Modbus protocol exposes the communication between the product and the
control system. Encryption, authentication or integrity of transmitted data are
not provided by the protocol. To prevent equipment to operate in an unsafe or
undesirable manner due to malicious activities the product must be positioned in
a trusted network, strictly limited and in a hosted portion of a network or control
system. The recommendation is also to restrict physical access to the product/
system to only allow authorized people to make changes to the system. Besides,
the user can setup system to trigger alarm when communication is interrupted
(device stops responding) and check if there are any unsafe condition.

17
AUTOMATIC TRANSFER SWITCH, OTM_C_21D
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4. Interface and Settings
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4.1 Buttons
Figure 11. Buttons
Table 5. Buttons
Button Function Remarks
I ON Transfer to LN1 Only available in automatic mode and remote
test mode
O OFF Transfer to 0 position
II ON Transfer to LN2
Auto Select autiomatic mode, fault clearance and reset
Transfer using bypass transfer delay and return delay.

18 AUTOMATIC TRANSFER SWITCH, OTM_C_21D
Table 6. LEDs
LED Display Status description
LN1/LN2 Source available Source available
OV: 5cycles/s;
UV:2cycles/s; Phase
missing:0.25cycles/s
OV: 5cycles/s; UV:2cycles/s; Phase missing:0.25cycles/s
Source not available Source not available
I/II Switch I or II closed Switch I or II closed
Switch I or II open Switch I or II open
Switching failure. Switching failure.
Auto Transfer switch in
automatic mode
Transfer switch in automatic mode
Transfer switch in test
mode or invalid setting
Transfer switch in test mode or invalid setting
Transfer switch in manual
mode
Transfer switch in manual mode
EMRG OFF Receiving emergency off
signals
Receiving emergency off signals
No emergency off signals
input
No emergency off signals input
Figure 12. LEDs
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4.2 Leds

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AUTOMATIC TRANSFER SWITCH, OTM_C_21D
Figure 13. Rotary switch, Ts and TBs
Figure 14. Rotary switch, OV and UV
Transfer delay Ts
The delay of transferring from the LN1 to the LN2
in automatic mode. The options are 0, 1, 2, 3, 5, 10,
15, 20, 25, and 30 seconds.
Return delay TBs
The delay of transferring from the LN2 to the LN1
in automatic mode. The options are 0, 5, 10, 20,
30, 60, 120, 300, 600, and 900 seconds.
Overvoltage threshold OV (%) and undervoltage
threshold UV (%)
The benchmarks of the OV and UV are the rated
voltage of the switch. When the voltage is higher
than the pre-set OV value or lower than the pre-
set UV value, the switch performs automatic
transfer.
The value of OV can be 5%, 10%, 15%, 20%, 25%,
and 30%.
The value of UV can be 5%, 10%, 15%, 20%, 25%,
and 30%.
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4.3 Rotary switch settings

20 AUTOMATIC TRANSFER SWITCH, OTM_C_21D
The 9-bit dip is used to control the switch for circuit testing, and the mismatch with
the load power supply will result in testing and transfer failure. Therefore, carefully
read this guide and set correct parameters based on the actual situation before using
this product.
Generator can not be used in no line priority. Keep generator setting “0” in this mode.
Table 7. Dip switch
The 9-bit dip switch is used to set the working
modes of transfer switch.
DIP
No.
Function Setting
1, 2 Pole setting 01 10 11 00
2 poles 3 poles 4 poles Invalid setting
3, 4 Mode setting 01 10 11 (Default) 00
No line priority Manual back
switching
Line priority LN1 Invalid setting
5, 6 Voltage setting 01 10 11 00
240VAC/415VAC 230VAC/400VAC 220VAC/380VAC Invalid setting
7 Frequency setting 0 1 (Default)
60Hz 50Hz
8 Generator selection 0 1 (Default)
No Yes
9 Generator stop
delay setting
0 1 (Default)
240s 30s
Figure 15. Dip switch
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4.4 Dip switch setting