Seg MRP2 User manual

MRP2 - Directional power relay

2 TB MRP2 07.98 E
Contents
1 Introduction and application
2 Features and characteristics
3 Design
3.1 Connections
3.1.1 Analog input circuits
3.1.2 Output relays
3.1.3 Blocking input
3.1.4 External reset input
3.2 LEDs
4 Working principle
4.1 Analog circuits
4.2 Digital circuits
4.3 Measuring principle
4.4 Demand imposed on the main current
transformers
5 Operations and settings
5.1 Display
5.2 Setting procedure
5.2.1 Pickup value for power increase (P>),
power decrease (P<) and reverse power (Pr)
5.2.2 Pickup value for undervoltage U<Pr of the
voltage dependent reverse power element
5.2.3 Tripping times for power increase (P>),
power decrease (P<) and reverse power (Pr)
5.2.4 Y/∆- Change-over of the input transformers
5.2.5 Circuit breaker failure protection tCBFP
5.2.6 Selection of the rated voltage
(100V/110V)
5.2.7 Display of the activation storage
(FLSH/NOFL)
5.2.8 Adjustment of the slave address
5.2.9 Setting of Baud rate (applies for Modbus
Protocol only)
5.2.10 Setting of parity (applies for Modbus
protocols only)
5.2.11 Blocking the protection functions and
assignment of the output relays
5.3 Indication of measuring values and fault
data
5.3.1 Indication of measuring values
5.3.2 Indication of fault data
5.3.3 Fault Recorder
5.4 Reset
5.5 Hints for the setting procedure
5.5.1 Setting of the power measuring circuits
switching point
6 Relay Testing and commissioning
6.1 Power-On
6.2 Testing the output relays
6.3 Checking the set values
6.4 Secondary injection test
6.4.1 Test equipment
6.4.2 Example of test circuit for MRP2 relay
6.4.3 Checking the input circuits and measured
values
6.4.4 Checking the operating and resetting
values of the relay
6.4.5 Checking the relay operating time
6.4.6 Test of the CB failure protection
6.4.7 Checking the external blocking and reset
functions
6.5 Primary injection test
6.6 Maintenance
7 Technical data
7.1 Measuring input circuits
7.2 Common data
7.3 Setting ranges and steps
7.3.1 Setting ranges and steps MRP2-1 and
MRP2-3
7.3.2 Setting ranges and steps MRP2-R1 and
MRP2-R3
7.3.3 Interface parameters
7.4 Output contact ratings
8 Order form
Important:
For additional common data of all MR-relays please
refer to manual "MR - Digital Multifunctional Relays".
This technical manual is valid for software version D13-4.12 (MRP2-1) or
D14-4.12 (MRP2-3) onwards!

TB MRP2 07.98 E 3
1 Introduction and application
The power relay MRP2 is used in 3-phase systems for
active power measurement.
In the single-phase relay type MRP2-1, the load of the
three phases is assumed to be symmetrical so that a
single phase power measurement can be realized.
For application fields (i.e. turbine movers) where two
reverse power switching points with higher precision
are required, the relay type MRP2-R is available.
Among others, the MRP2-relays serve:
• for supervision of load flow between two systems.
(MRP2)
If the generated power of one system fails, unimportant
consumers have to be disconnected by the power re-
lay. Thereby the mains is stabilised and the supply of
important consumers maintained. If gen.-sets are oper-
ating in parallel, these consumers can be disconnected
if the load remains below the set minimal value or - in
peak load operating mode - they can be connected if
a limit value for the mains power is exceeded.
• as reverse power relay to protect turbines and Diesel
gen.-sets from reverse power if this prime mover fails.
(MRP2 and MRP2-R)
For generators operating in parallel with a mains or
another generator, it is imperative to supervise the
power direction. If for example the prime mover fails
the alternator operates as a motor and drives the prime
mover (diesel or turbine). The MRP2 "recognizes" the
reverse of the power direction and - in case of this er-
ror - switches off the alternator. This way, power losses
and damages of the prime mover are avoided.
• as voltage dependent reverse power relay for mains
decoupling
The criterium for tripping the voltage-dependent reverse
power element is the reverse power with simultaneous
voltage decrease as a result of an external mains fault.
Decoupling prevents external mains faults from affect-
ing the own mains section. Internal faults are selec-
tively detected by other protection devices.
2 Features and characteristics
Unit MRP2 still has another feature besides those de-
scribed in the general MR-description, namely:
• Measuring of the actual power by means of multi-
plication and integration of the instantaneous val-
ues of current and voltage.
• Correct measuring even at unequally loaded
phases (MRP2-3).
• Switchable measuring for delta or star connection
of v.t.'s.
• Indication of current, voltage and power
• Serial interface
• Three adustable power switching-points.
• voltage dependent reverse power element
• Plug-in type design with automatic short-circuiters
for current transformer circuits.
• Circuit Breaker failure protection
• Storing of trip values and breaking times (tCBFP) of
eight fault events
• Ability of serial data transmission via RS485 inter-
face optional with SEG RS485 Pro Open Data Pro-
tocol or Modbus Protocol

4 TB MRP2 07.98 E
3 Design
3.1 Connections
Fig. 3.1: Connection diagram MRP2-1 and MRP2-R1 (Star-/Delta adjustment has to be set to DELTA)
Fig. 3.2: Connection diagram MRP2-3 and MRP2-R3 (Star-/Delta adjustment has to be set to Y)

TB MRP2 07.98 E 5
Fig 3.3: Voltage transfomer in V-connection
3.1.1 Analog input circuits
The analog input signals of the conductor currents IL1
(B3-B4), IL2 (B5-B6), IL3 (B7-B8) and the phase voltages
U1 (A3), U2 (A5), U3 (A7) with A8 as starpoint are
each transmitted to the protection device MRP2-3 by
means of separate input transformers (star connection).
At the single-phase version of unit MRP2-1 the input
signals are also transmitted via separate input trans-
formers: IL1 (B3-B4); U1 (A3-A4).
The constantly measured current values are galvani-
cally decoupled, filtered by a low pass-filter and finally
fed to the analog/digital converter.
3.1.2 Output relays
The
MRP2 is equipped with 5 output relays. Apart
from the relay for self-supervision, all protective func-
tions can be optionally assigned:
• Relay 1: C1, D1, E1 and C2, D2, E2
• Relay 2: C3, D3, E3 and C4, D4, E4
• Relay 3: C5, D5, E5
• Relay 4: C6, D6, E6
• Self-supervision C7, D7, E7
All trip and alarm relays are working current relays, the
relay for self supervision is an idle current relay.
3.1.3 Blocking input
The function for blocking can be parameterized arbi-
trary. When an auxiliary voltage is connected to
D8/E8 those relay functions will be blocked which
were parameterized before (refer to chapter 5.2.6).
3.1.4 External reset input
Please refer to chapter 5.4

6 TB MRP2 07.98 E
Fig.3.4: Front plate MRP2-1 and MRP2-R1
Fig. 3.5: Front plate MRP2-3 and MRP2-R3
3.2 LEDs
Measuring values will be indicated on display together
with the LEDs P, L1, L2, L3, U and I (refer to chapter
5.3).
The MRP2 provides one LED to indicate the power di-
rection (green and red arrow). Green indicates gen-
erator power, red indicates reverse power.
For setting and indication of protection trippings the
LEDs beneath the push buttons are used.
The five LEDs below push-button <SELECT/RESET> are
bi-coloured: green relates to P>, P<, Pr, U<Pr, ∆/Y, red
relates to tp>, tp< and tpr and tU<Pr.
The LED marked with letters RS lights up during setting
of the slave address of the device for serial data com-
munication.

TB MRP2 07.98 E 7
4 Working principle
4.1 Analog circuits
The incoming currents from the main current transform-
ers on the protected object are converted to voltage
signals in proportion to the currents via the input trans-
formers and burden. The noise signals caused by in-
ductive and capacitive coupling are supressed by an
analog R-C filter circuit.
The analog voltage signals are fed to the A/D-con-
verter of the microprocessor and transformed to digital
signals through Sample- and Hold- circuits. The meas-
uring value detection takes with a sampling frequency
of 900 Hz (1080 Hz), namely, a sampling rate of
1.11 ms (0.93 ms) for every measuring quantity at 50
Hz (60 Hz).
4.2 Digital circuits
The essential part of the MRP2 relay is a powerful mi-
crocontroller. All of the operations, from the analog
digital convertion to the relay trip decision, are carried
out by the microcontroller digitally.
By means of a special protective routine stored in the
EPROM, the microprocessor processes currents and
voltages at the analog inputs and then - based on the
measured values - calculates the existing power.
The measured power is permanently compared with
the threshold value stored in the parameter memory
(EEPROM - Electrically Erasable Programmable Read-
Only Memory). If a measured power exceeds the
pickup value, an alarm is given and after the set trip
delay has elapsed, the corresponding trip relay is acti-
vated.
The relay setting values for all parameters are stored in
a parameter memory (EEPROM), so that the actual re-
lay settings cannot be lost, even if the power supply is
interrupted.
The microprocessor is supervised through a built-in
"watch dog" timer. In case of a failure the watch dog
timer resets the microprocessor and gives an alarm
signal, via the output relay "self supervision".
4.3 Measuring principle
Through multiplication of the actual current and voltage
values p(t) = u(t) ⋅i(t), the microprocessor calculates the
phase power. 18 instantaneous values are measured
and recorded per cycle. Afterwards the power value
during one cycle is determined.
PTPt dt
=⋅
∫
1
()
Consequently, the total three phase current is calcu-
lated from: Ptotal = P1 + P2 + P3
t
u(t)
t
i(t)
t
t
p(t) = u(t) i(t)
P1
Tp(t) dt
=⋅ ⋅
∫
⋅
Fig. 4.1: Power measurement
4.4 Demand imposed on the main
current transformers
The current transformers must be designed in such a
manner that they are precisely dimensioned for pure re-
verse power in the lower range especially with the
MRP2-R. We therefore recommend the use of measur-
ing transformers which are at least type 1M5. The low
energy consumption of the MRP2-R of <0.2 VA has a
positive effect on the design of the current transformers.

8 TB MRP2 07.98 E
5 Operations and settings
5.1 Display
Function Display shows Pressed pushbutton Corresponding LED
Normal operation SEG
Measured operating values
phase voltages,
phase currents,
power and power direction
Actual measured
voltage UL1, UL2, UL3,
UL12, UL23, UL31
current IL1, IL2, IL3
power Ptot, PL1, PL2, PL3
<SELECT/RESET>
one time for each value
L1/U, L2/U, L3/U,
L1/I, L2/I, L3/I
→← P/L1/L2/L3
Setting values
delta/star-connection adjustment
DELT or Y <SELECT/RESET><+><-> ∆/Y
power increase
trip delay for power increase
setting value in PN
setting value in seconds
<SELECT/RESET>
one time for each value
P>
tP>
power decrease/reverse power
trip delay for power decrease
setting value in PN
setting value in seconds
<SELECT/RESET>
one time for each value
P<
tP<
reverse power
trip delay for reverse power
setting value in PN
setting value in seconds
<SELECT/RESET>
one time for each value
Pr
tPr
undervoltage U<Pr
trip delay tU<Pr
setting value in volts
setting value in seconds
<SELECT/RESET>
one time for each value
U<Pr
tU<Pr
Function blockade EXIT <+> until max. setting
value
LED of blocked parame-
ter
Circuit breaker failure protection CBFP <SELECT/RESET><+><-> L1, L2, L3, →← *
P>, P<, Pr, U<Pr
Indication of memorized pickup FLSH/NOFL <SELECT/RESET><+><->
Selection of rated voltage 100 V/110 V <SELECT/RESET><+><-> U
Slave address of serial
interface
1-32 <SELECT/RESET><+><-> RS
Recorded fault data of power Measured values in the
instant of tripping
<SELECT/RESET>
one time for each value
L1, L2, L3, P>, P<, Pr*
→←
Recorded fault data of voltage
U1, U2, U3
Measured values in volts <SELECT/RESET>
one time for each value
L1, L2, L3 and U*
Recorded fault data of current
I1, I2, I3
Measured values related
to In
<SELECT/RESET>
one time for each value
L1, L2, L3 and I*
Save parameter? SAV? <ENTER>
Save parameter! SAV! <ENTER> for about 3 s
Software version First part (e.g. D16-)
Second part (e.g. 5.01)
<TRIP>
one time for each part
Manual trip TRI? <TRIP>
three times
Inquire password PSW? <SELECT/RESET>
<+><-><ENTER>
Relay tripped TRIP <TRIP>
or after fault tripping
L1, L2, L3, →← *
P>, P<, Pr
Secret password input XXXX <SELECT/RESET>
<+><-><ENTER>
System reset SEG <SELECT/RESET>
for about 3 s
Table 5.1: possible indication messages on the display
* The units MRP2-1 and MRP2-R1 with single-phase power measurement have only the LED P available
instead of LED L1, L2 and L3

TB MRP2 07.98 E 9
5.2 Setting procedure
After push button <SELECT/RESET> has been pressed,
always the next measuring value is indicated. Firstly
the operating measuring values are indicated and then
the setting parameters. By pressing the <ENTER> push
button the setting values can directly be called up and
changed.For parameter setting a password has to be
entered. (please refer to chapter 4.4 of description
"MR-Digital Multifunctional Relays")
5.2.1 Pickup value for power increase
(P>), power decrease (P<) and
reverse power (Pr)
After setting of the pickup value to supervise power in-
crease, (P>), power decrease (P<) and reverse power
(Pr), the display indicates a value that is related to the
three phase nominal power PNof the unit.
This means:
Pickup value = indicated value x nominal power
(PN= √3 ⋅UN⋅INwith UN= phase to phase voltage).
Push-buttons <+> or <-> can be pressed to change,
<ENTER> to store the indicated value.
It is also possible to use the power decrease relay (P<)
as a second reverse power relay. If applied for reverse
power protection, the parameters for P< have to be
adjusted to negative values, the value which is used
for Pr must be set positive.
In the MRP2-R (reverse power relay with increased
precision) unit version, the value for a power increase
in forward direction P> can only be set to 0,5 x Pn
and must therefore - as a rule - be blocked by means
of setting EXIT.
The functions P> and Pr are blocked each by incre-
menting via push-button <+> until Exit appears on
the display and storage with push-button <ENTER>. P<
is deactivated by incrementing the set value via push-
button <-> until EXIT appears on the display. This en-
try as well has to be stored via push-button <ENTER>.
If trip time is set to exit but not so the threshold belong-
ing to it, tripping is blocked. In case of failure, the be-
longing alarm relay picks up nevertheless.
Tripping takes place if the sum total of individual loads
exceeds or drops below the set value.
5.2.2 Pickup value for undervoltage
U<Pr of the voltage dependent
reverse power element
When the threshold value of the secondary voltage
excitation is being adjusted, the display shows a re-
sponse value in volt.
The voltage-dependent reverse power element is ex-
cited when the device measures a reverse power
greater than Pr (set value see 5.2.1) and a secondary
voltage smaller than U<Pr in at least one phase.
The displayed set values can be changed with the
keys <+> and <-> and stored with <ENTER>.
Fig. 5.1: Reverse power element Pr and voltage dependent
reverse power element PrU<
5.2.3 Tripping times for power increase
(P>), power decrease (P<) and
reverse power (Pr)
After setting of the tripping times a value indicated in
seconds is shown on the display. The required time de-
lay can be entered by means of push-buttons <+> and
<-> and is stored via <ENTER>.

10 TB MRP2 07.98 E
5.2.4 Y/∆- Change-over of the input
transformers
The voltage sensing circuits of the MRP2 may be con-
nected in either star or delta configuration. The relay
rated voltage, UN, refer to the line-line voltage in the
star connection. When the relay is connected in the
delta connection the maximum line-to-line voltage must
be reduced to 1/√3 x UN. During parameter setting
the connection configuration either in star or delta has
to be specified.
For the single-phase type (MRP2-1) phase-to-phase
voltage U12 or phase-to-neutral voltage U1E can be
connected to terminals A3/A4. Pay attention to the
correct setting of the star or delta adjustment.
U12
U23
U31
A3
A4
A5
A6
A7
A8
b
c
a
secondary side of the
mains voltage transformer
Fig. 5.2: Input transformers in delta-connection (MRP2-3)
U
U
U
A3
A4
A5
A6
A7
A8
a
b
c
1E
2E
3E
secondary side of the
mains voltage transformer
Fig. 5.3: Input transformers in star-connection (MRP2-3)
5.2.5 Circuit breaker failure protection
tCBFP
The CB failure protection is based on supervision of
phase currents during tripping events. Only after trip-
ping this protective function becomes active. The test
criterion is whether all phase currents are dropped to
<1% x INwithin tCBFP (Circuit Breaker Failure Protection -
adjustable between 0.1 - 1.6s). If not all of the phase
currents have dropped to <1%xINwithin this time, CB
failure is detected and the related relay activated. The
CB failure protection function is deactivated again as
soon as the phase currents have dropped to <1%xIN
within tCBFP
5.2.6 Selection of the rated voltage
(100V/110V)
Relay types with a rated voltage of 100 V can optio-
nally be adjusted to 110 V rated voltage. This simpli-
fies calculation of the trip value of 110 V systems. This
parameter can be changed by push buttons <+> and
<-> and saved by pressing <ENTER>.
5.2.7 Display of the activation storage
(FLSH/NOFL)
If after an activation the existing power drops again
below the pickup value, e.g. P>, without a trip has
been initiated, LED P> signals that an activation has
occured by flashing fast. The LED keeps flashing until it
is reset again (push button <RESET>). Flashing can be
suppressed when the parameter is set to NOFL.
5.2.8 Adjustment of the slave address
Pressing push buttons <+> and <-> the slave address
can be set in the range of 1 - 32. LED RS lights up dur-
ing setting procedure.

TB MRP2 07.98 E 11
5.2.9 Setting of Baud rate (applies for
Modbus Protocol only)
Different transmission rates (Baud rate) can be set for
data transmission via Modbus protokol.
The rate can be changed by push buttons <+> and
<-> and saved by pressing <ENTER>.
5.2.10 Setting of parity (applies for
Modbus protocol only)
The following three parity settings are possible :
• "EVN" = even
• "ODD" = odd
• "NO" = no parity check
The setting can be changed by push buttons <+> and
<-> and saved by pressing <ENTER>.
5.2.11 Blocking the protection functions
and assignment of the output
relays
The blocking function of the MRP2 can be set accord-
ing to requirement. By applying the voltage (in the
range from aux. voltage) to D8/E8, the functions cho-
sen by the user are blocked. Setting of the parameter
should be done as follows:
Setting of blocking input:
• Following the simultaneous activation of the
<ENTER> and <TRIP> keys the display shows the
text BL=1 (the blocking function is active if auxiliary
voltage is fed) or BL=0 (the blocking function is ac-
tive if auxiliary voltage is missing).
• By pressing push buttons <+> <-> the value dis-
played can be changed.
• The changed value is stored by pressing <ENTER>
and entering the password.
Function Display
BLOC Blockage activ BL=1
Table 5.2: Default settings blocking parameters
Blocking the protection functions:
• When pressing push buttons <ENTER> and <TRIP>
at the same time, message "BLOC" is displayed (i.e.
the respective function is blocked) or "NO_B"
(i.e. the respective function is not blocked). The LED
allocated to the first protection function P> lights red.
• By pressing push buttons <+> <-> the value dis-
played can be changed.
• The changed value is stored by pressing <ENTER>
and entering the password.
• By pressing the <SELECT/RESET> push button, any
further protection function which can be blocked is
displayed.
• Thereafter the blocking menu is left by pressing
<SELECT/RESET> again.
Function Display LED/Colour
P> power in-
crease
BLOC P> yellow
P< power de-
crease
BLOC P< yellow
Pr reverse
power
BLOC Pr yellow
U<Pr undervoltage BLOC U<Pr red
CBFP C.B. failure
protection
NO_B
Table 5.3: Default settings of blocking functions
Assignment of the output relays:
Unit MRP2 has five output relays. The fifth output relay
is provided as permanent alarm relay for self supervi-
sion is normally on. Output relays 1 - 4 are normally
off and can be assigned as alarm or tripping relays to
the power functions which can either be done by us-
ing the push buttons on the front plate or via serial in-
terface RS485. The assignment of the output relays is
similar to the setting of parameters:
• By pressing push button <SELECT/RESET> in block-
ing mode again, the assignment mode is selected.

12 TB MRP2 07.98 E
Definition:
Alarm relays are activated at pickup.
Tripping relays are only activated after elapse of the
tripping delay.
The relays are assigned as follows:
• LEDs P>, P< and Pr are two-coloured and light up
green when the output relays are assigned as alarm
relays and red as tripping relays.
After the assignment mode has been activated, first
LED P> lights up green. Now one or several of the
four output relays can be assigned to power element
P> as alarm relays.
• Indication "1_ _ _" means that output relay 1 is as-
signed to this power element. When the display
shows "_ _ _ _", no alarm relay is assigned to this
power element.
• The assignment of output relays 1 - 4 to the power
elements can be changed by pressing <+> and <->
push buttons.
• The selected assignment can be stored by pressing
push button <ENTER> and subsequent input of the
password.
• By pressing push button <SELECT/RESET>, LED I>
lights up red. The output relays can now be as-
signed to this power element as tripping relays. Re-
lays 1 - 4 are selected in the same way as de-
scribed before.
• By repeatedly pressing of the <SELECT/RESET>
push button and assignment of the relays all ele-
ments can be assigned separately to the relays.
The blocking and assignment mode can be terminated
at any time by pressing the <SELECT/RESET> push
button for some time (abt. 3 s).
Note:
• The function of jumper J2 described in general de-
scription "MR Digital Multifunctional Relays" has no
function. For relays without assignment mode this
jumper is used for parameter setting of alarm relays
(activation at pickup or tripping).
• A form is attached to this description where the set-
ting requested by the customer can be filled-in. This
form is prepared for telefax transmission and can
be used for your own reference as well as for tele-
phone queries.
Relay function Output relays Display- Lighted LED
1234
indication
P> alarm X _ 2 _ _ P>: green
tripping X 1 _ _ _ P>: red
P< alarm X _ 2 _ _ P<: green
tripping X 1 _ _ _ P<: red
Pr alarm X _ _ 3 _ Pr: green
tripping X 1 _ _ _ Pr: red
U<Pr alarm X _ _ 3 _ U<Pr: green
tripping X 1 _ _ _ U<Pr: red
tCBFP tripping X _ _ _ 4
Table 5.4: Example of assignment matrix of the output relay (default settings).

TB MRP2 07.98 E 13
5.3 Indication of measuring values and
fault data
5.3.1 Indication of measuring values
During normal service, the following measuring values
of the MRP2-3 can be indicated:
• Total three-phase active power (LEDs L1, L2, L3 green)
• Active power in phase L1 (LED L1 green)
• Active power in phase L2 (LED L2 green)
• Active power in phase L3 (LED L3 green)
In star-connection only:
• Phase-to-neutral voltage in phase L1
(LED U and L1 green)
• Phase-to-neutral voltage in phase L2
(LED U and L2 green)
• Phase-to-neutral voltage in phase L3
(LED U and L3 green)
In delta-connection only:
• Phase-to-phase voltage U12 (LED U, L1, L2 green)
• Phase-to-phase voltage U23 (LED U, L2, L3 green)
• Phase-to-phase voltage U31 (LED U, L1,L3 green)
Phase currents:
• Current in phase 1 (LED I and L1 green)
• Current in phase 2 (LED I and L2 green)
• Current in phase 3 (LED I and L3 green)
The following measuring values of the MRP2-1 can be
indicated during normal service:
• Total three-phase active power (LED P green)
In star connection:
• phase-to-neutral voltage (LED U green)
In delta connection:
• phase-to-phase voltage (LED U green)
• phase current (LED I green)
5.3.2 Indication of fault data
All faults detected by the relay are indicated on the
front plate optically. For this purpose, the four LEDs (L1,
L2, L3, →←) and the four function LEDs (P>, P<, Pr,
U<Pr) are equipped at MRP2 and MRP2-R1. If, for ex-
ample a reverse power occurs, first the LEDs L1, L2, L3
will light up. LED Pr lights up at the same time. After
tripping the LEDs are lit permanently.
At unit MRP2-1 and MRP2-R1 the two LEDs (P, →←)
and the four functional LEDs (P>, P<, Pr, U<Pr) are
equipped to display the detected fault data.

14 TB MRP2 07.98 E
5.3.3 Fault Recorder
When the relay is energized or is energized or trips,
all fault data and times are stored in a non-volatile
memory manner. The MRP2 is provided with a fault
value recorder for max.eight fault events. In the event
of additional trippings always the oldest data set is
written over.
For fault indication not only the trip values are re-
corded but also the status of LEDs. Fault values are in-
dicated when push buttons <-> or <+> are pressed
during normal measuring value indication.
• Normal measuring values are selected by pressing
the <SELECT/RESET> button.
• When then the <-> button is pressed, the latest fault
data set is shown. By repeated pressing the <->
button the last but one fault data set is shown etc.
For indication of fault data sets abbreviations FLT1,
FLT2, FLT3, ... are displayed (FLT1 means the latest
fault data set recorded).
• By pressing <SELECT/RESET> the fault measuring
values can be scrolled.
• By pressing <+> it can be scrolled back to a more
recent fault data set. At first FLT8, FLT7, ... are al-
ways displayed.
When fault recording is indicated (FLT1 etc), the
LEDs flash in compliance with the stored trip infor-
mation, i.e. those LEDs which showed a continuous
light when the fault occured are now blinking to
indicate that it is not a current fault. LEDs which
were blinking during trip conditions, (element had
picked up) just briefly flash.
• If the relay is still in trip condition and not yet reset
(TRIP is still displayed), no measuring values can be
shown.
• To delete the trip store, the push button combina-
tion <SELECT/RESET> and <-> has to be pressed
for about 3 s. The display shows 'wait'.
Recorded fault values at MRP2-3:
Indicated quantity correspon-
ding LED
Unit
Total power L1, L2, L3 [x PN]
Power in phase L1, L2, L3 * L1, L2, L3 [x PN]
Phase-to-phase voltage in
delta connection
L1/L2, U
L2/L3, U
L3/L1, U
[V]
Phase-to-neutral voltage in
Y connection
L1, L2, L3, U [V]
Phase currents L1, L2, L3 L1, L2, L3, I [x IN]
C.B. tripping time
1)
[s]
* only in Y connection
Recorded fault values at MRP2-1:
Indicated quantity correspon-
ding LED
Unit
Total power P [x PN]
Phase-to-phase voltage in
delta connection
U [V]
Phase-to-neutral voltage in
Y connection
U [V]
Phase current I [x IN]
C.B. tripping time
1)
[s]
1)
C.B. tripping time:
Time between pickup and release of the low set
element. This value is only displayed for <1% x IN

TB MRP2 07.98 E 15
5.4 Reset
Unit
MRP2 has the following three possibilities to reset
the display of the unit as well as the output relays at
jumper position J3=ON.
Manual Reset
• Pressing the push button <SELECT/RESET> for some
time (about 3 s).
Electrical Reset
• Through applying auxiliary voltage to C8/D8.
Software Reset
• The software reset has the same effect as the
<SELECT/RESET> push button (see also communica-
tion protocol of RS485 interface).
The display can only be reset when the pickup is not
present anymore (otherwise "TRIP" remains in display).
During resetting of the display the parameters are not
affected.

16 TB MRP2 07.98 E
5.5 Hints for the setting procedure
5.5.1 Setting of the power measuring
circuits switching point
The fact that the relay has to pickup for example at an
alternator reverse power of 5% does not necessarily
mean that the setting value of the MRP2 is also 5%.
Due to the transformer ratio, the switchpoints' setting
value must first be calculated.
Calculation of the setting value
Necessary data:
PGEN[kW] Active power of the generator in kW
it is calculated from the apparent power
of the generator SGEN according to:
PGEN = SGEN ⋅COS ϕ
PMRP2 [kW] Reference power of the MRP2 in kW
It is calculated from
INNominal current of the relay
UNNominal voltage of the relay
nIRatio of the current transformer
nURatio of the voltage transformer
for 4 wire system according to
PMRP2 = √3 x INx UNx nIx nU
with UN= phase to phase voltage
If PREV [%] is the desired reverse-power value in % refer-
ring to the active power of the generator, then the
value to be adjusted on the relay is calculated as per
following formula:
adjustment value in % = PkW
P
GEN
REV
P [kW] [%]
MRP1
[]
⋅
Calculation-example 1
active power of the generator
PGEN = 625 kVA x 0.8 = 500 kW
rated current of MRP2 I
N
= 5 A
rated voltage of MRP2 U
N
= 400 V
(phase-to-phase voltage)
ratio of the current
transformer nI= 1000 A / 5 A
= 200
⇒reference power of the unit
PMRP2 = √3 x 5A x 400 V x 200 = 690 kW
If the relay should respond at a reverse power of 5%
the adjustment value can be calculated in the follow-
ing way:
adjustment value (% of scale) = 500 kW
690 kW x5% =
3.62%
In the previous example the relay MRP2 has to be ad-
justed to 4%, so that it responds to a generator reverse-
active power of 5%. The more sensitive relay version
MRP2-R can be adjusted to 3.7%
Calculation example 2
active power of the generator
PGEN = 1875 kVA x 0.8 = 1500 kW
nominal current of MRP2 I
N
=5A
nominal voltage of MRP2
(phase-to-phase voltage) UN= 100 V
Ratio of
current transformer nI= 150 A / 5 A
=30
voltage transformer nU= 10 kV / 100 V
= 100
⇒reference voltage of the unit
PMRP2 = √3 x 5 A x 100 V x 30 x 100 = 2598 kW
If the relay should pickup at reverse power greater
than 3% (refered to the active power of the generator)
the adjustment value can be calculated in the follow-
ing way:
adjustment value % = 1500 kW
2598 kW x 3% = 1.73%
In the foregoing example the relay MRP2 has to be
adjusted to 2%.
The more sensitive relay version MRP2-R can be adjus-
ted to 1.8%.

TB MRP2 07.98 E 17
6 Relay Testing and
commissioning
The following test instructions should help to verify the
protection relay performance before or during commis-
sioning of the protection system. To avoid a relay
damage and to ensure a correct relay operation, be
sure that:
• the auxiliary power supply rating corresponds to the
auxiliary voltage on site.
• the rated current and rated voltage of the relay cor-
respond to the plant data on site.
• the current transformer circuits and voltage trans-
former circuits are connected to the relay correctly.
• all signal circuits and output relay circuits are con-
nected correctly.
6.1 Power-On
NOTE!
Prior to switch on the auxiliary power supply, be sure
that the auxiliary supply voltage corresponds with the
rated data on the type plate.
Switch on the auxiliary power supply to the relay and
check that the message "SEG" appears on the dis-
play and the self supervision alarm relay (watchdog) is
energized (Contact terminals D7 and E7 closed).
6.2 Testing the output relays
NOTE!
Prior to commencing this test, always block the output
circuits or interrupt in another way the output circuits
which can cause the tripping of the circuit breaker if
the breaker operation during this test is not desired.
By pressing the push button <TRIP> once the display
shows you the first part of the software version of the
relay (e.g. D08-). By pressing the push button <TRIP>
twice the display shows the second part of the soft-
ware version of the relay (e.g. 4.01). The software
version should be quoted in all correspondence. After
you have got a message "PSW?" on the display by
pressing the push button <TRIP> once more please en-
ter the correct password to proceed with the test. After
that the message "TRI?" will follow. Confirm this testing
by means of pressing push button <TRIP> again. All
output relays should then be activated and the self su-
pervision alarm relay (watchdog) be deactivated one
after another with a time interval of 1 second. Thereaf-
ter, reset all output relays by pressing the push button
<SELECT/RESET>.
6.3 Checking the set values
As input energizing quantities for three phase power
relay MRP2-3, three phase voltages and currents will
be applied to relay input circuits.
By repeatedly actuating the push button <SELECT> all
relay set values may be checked For detailed informa-
tion, please refer to chapter 5.
Depending on the system conditions and the voltage
transformer used, three phase voltages can be con-
nected to the relay input circuits with either star or
delta connection. In case of a star connection the
phase-to-neutral voltage will be applied to the voltage
input circuits, while the phase-to-phase voltages will be
connected to the voltage input circuits in case of a
delta connection. The voltage input connection can be
set as a parameter, and should agree with the actual
voltage input connection:
Y: Star connection. Phase-to-neutral voltages will
be measured and evaluated.
Delt: Delta connection. Phase-to-phase voltages will
be measured and evaluated.
Phase-to-phase voltages or phase-to-neutral voltage will
be connected to the relay MRP2-1 when changeover
star/delta correction.
NOTE!
For single phase power relay MRP2-1, if delta connec-
tion is chosen, current in phase 1 (IL1) should be con-
nected to input terminals B3/B4 and phase-to-phase
voltage between phase 1 and phase 2 (U12) should be
connected to input terminals A3/A4. If star connection
is chosen, the current in phase 1 (IL1) should be con-
nected to input terminals B3/B4 and phase-to-neutral
voltage between phase 1 and neutral (U1E) should be
connected to input terminals A3/A4.
6.4 Secondary injection test
6.4.1 Test equipment
•
Voltmeter, ammeter and wattmeter with class 1 or better
• Auxiliary power supply with the voltage correspond-
ing to the rated data on the type plate
• Single-phase or three-phase current supply unit
(adjustable from 0 to 2 x In)
• Single-phase or three phase voltage supply unit
(adjustable from 0 to 1.2 x Un)
• Timer to measure the operating time (Accuracy class
10 ms)
• Switching device
• Test leads and tools

18 TB MRP2 07.98 E
6.4.2 Example of test circuit for MRP2
relay
For testing power relays, you need both current and
voltage input signals with adjustable phase shifting.
Figure 1 shows an example of a single phase test cir-
cuit with adjustable voltage and current energizing the
MRP2 relay under test.
For testing the power relay, the input voltage shall be
applied to the relay with a constant value within its ef-
fective range (U = Un or U = Un/√3). The input cur-
rent and phase angle shall be appropriately varied.
In figure 6.1 the relay voltage connection is supposed
to be set to star connection and a single phase test
circuit will be used to test a three phase power relay
MRP2-3 or a single phase power relay MRP2-1.
~=
MRP1
Versorgung
Supply
Versorgung
Supply
L+/L L-/N
C9 E9 D9
Extern Reset
External Reset Blockiereingang Blocking Input
L+/L
C8 L-/N D8 L+/L E8
N
G
P
N
G
P
Serielle Schnittstelle
Serial Interface
Selbstüberwachung
Selfsupervision
P<
Pr
P>
Warnung / Anzeige
Alarm / Indication
Auslösen
Trip Signal
D1
C1
E1
D2
C2
E2
D4
C4
E4
D5
D6
C5
C6
E5
E6
B3
I1
I2
I3
U
U
U
D7
C7
E7
~
A
1
2
Timer
8
Start
-
-
+
Stop
+
2
**
*
*
*
**
*
46
5
7
B5
B6
B7
A3
A4
A5
A6
A7
A8
B8
B4
9
3
1E
2E
3E
V
W
Fig. 6.1: Test circuit
Great care must be taken as to connect the test current
and test voltage to the relay in correct polarity. In fig-
ure 6.1 the relay and test source polarity are indicated
by a * mark near the terminals. The markings indicate
that the relay will measure a forward active power
when the voltage drops from polarity to non-polarity in
the voltage input circuit and the current flows from po-
larity to non-polarity in the current input circuit in case
of a unity power factor.
The power at MRP2-1 (∆-setting) will be calculated as
follows:
PTot = I1x U12 + I3x U32 , this means: phase 2 is used
as reference current.
Meanwhile the displayed power will not be changed
if current I2changes.

TB MRP2 07.98 E 19
6.4.3 Checking the input circuits and
measured values
The active power measured by MRP2 is related to the
rated power of the relay PN:
P
N
Un IN
=⋅ ⋅
33
Inject a current of rated value (1A for IN= 1A) in
phase 1 (terminals B3-B4) and apply a voltage of
Un/√3 to terminals A3/A4. The input voltage and
current should be in phase (unity power factor). Check
the measured power, voltage and current on the dis-
play by pressing the push button <SELECT>. The
power to be measured in this case should be 0.33 x
PNfor three phase power relays MRP2-3 and 1.00 x
PNfor single phase power relays MRP2-1 respectively.
The voltage to be measured is Un/√3 and current to
be measured 1 x IN.
Exchange the current input terminals B3/B4. The
power to be measured in this case should be - 0.33 x
PNfor three phase power relays MRP2-3 and - 1.00 x
PNfor single phase power relays MRP2-1. The voltage
to be measured is UN/√3 and current to be measured
1 x IN.
Compare the values of current, voltage and power
shown in display with the measured values of amme-
ter, voltmeter and active power meter. The deviations
of current and voltage measurement must not exceed
3%. The deviation of active power measurement must
not exceed 5%.
If possible, perform the test for different phase angles
and check the active power to be measured.
6.4.4 Checking the operating and reset-
ting values of the relay
Apply rated voltage on input terminals A3/A4.
Gradually increase (decrease) the current in phase 1
until the relay starts, i.e. at the moment when the LED
P> (or P<) lights up or the alarm output relay P> (or P<)
is activated. Read-off the operating active power from
wattmeter. The deviation must not exceed 5% of the set
operating value under the condition of reactive part <
50%.
Furthermore, gradually decrease (increase) the current
until the relay resets, i.e. the alarm output relay P> (or
P<) is de-energized.
For ascertaining the resetting value, increase (decrease)
gradually the test current until the output relay P> (P<)
de-energizes. For overload the resetting value must be
>97%. For P< the value must be <103%.
Checking the operating and resetting values at
reverse power
This test can be done similarly , only CT terminals
B3/B4 have to be changed. Lighting up of LED Pr and
energizing of alarm output relay Pr (terminals D6/E6)
have to be observed. Values displayed to be negative
in sign.
Checking the operating and resetting values at volt-
age-dependent reverse power
When the reverse power element is excited (see
above), the measuring voltage is decreased. If the
voltage-dependent reverse power element picks up,
lighting-up of the LED, tripping of the jumpered alarm
and tripping relays as well as the voltage value at
tripping must be checked.
6.4.5 Checking the relay operating time
To check the relay operate time, a timer to is be con-
nected to the trip relay contact. The timer should be
started simultaneously with the current injection in the
current input circuit and stopped by the trip relay con-
tact. Apply rated voltage to the relay and set the cur-
rent to a value corresponding to twice the operate
value and inject the current instantaneously. The oper-
ate time measured by timer should have a deviation
<3% of the set value or 20 ms.
Repeat the test on all phases and for all relay functions
(Over-power P>, Under-power P< and Reverse power
Pr) in the same manner.

20 TB MRP2 07.98 E
6.4.6 Test of the CB failure protection
For testing the tripping time the rated voltage has to be
applied and a test current of about 2 times the rated
current to be injected. The timer is started upon trip-
ping of the relay of a protection function (P<, P>, P)
and stopped as soon as the relay for the CB failure
protection has picked up. Message "CBFP" is dis-
played. The tripping time ascertained by the timer
should not deviate more than 1% or, at short trip de-
lay, less than 10 ms from the set tripping time.
Alternatively, the timer can be started when the aux.
voltage and the test current are injected simultaneous-
ly. The timer stops when the corresponding output re-
lay for circuit breaker failure protection trips.
In this case the previously measured tripping delay
(see section 6.4.5) has to be subtracted from the total
tripping time measured.
6.4.7 Checking the external blocking
and reset functions
At MRP2 relays, all relay functions will be inhibited by
external blocking input. To test the blocking function:
Apply auxiliary supply voltage to the external blocking
input of the relay (terminals E8/D8). Apply a test volt-
age and inject a test current which could cause a trip-
ping. Observe that there is no trip and alarm.
Remove the auxiliary supply voltage from the blocking
input. Apply a test voltage and inject a test current to
make the relay tripped (Message TRIP on the dis-
play). Interrupt the test current and apply auxiliary sup-
ply voltage to extern reset input of the relay (terminals
C8/D8). The display and LED indications should be
reset immediately.
6.5 Primary injection test
Generally, a primary injection test could be carried out
in the similar manner as the secondary injection test
above described. With the difference that the pro-
tected power system should be, in this case, con-
nected to the installed relays under test on line, and
the test currents and voltages should be injected to the
relay through the current and voltage transformers with
the primary side energized. Since the cost and poten-
tial hazards are very high for such a test, especially if
staged fault tests are intended, primary injection tests
are usually limited to very important protective relays in
the power system.
Because of its powerful combined indicating and
measuring functions, you have still the possibilities to
test the MRP2 relay in the manner of a primary injec-
tion without extra expenditures and time consumption.
In actual service, for example, the measured current
and voltage values as well as the measured active
power value may be compared phase by phase with
the measuring devices on the switch-board panel to
verify that the relay works and measures correctly and
to verify that the relay is connected to the power sys-
tem with the correct polarity.
6.6 Maintenance
Maintenance testing is generally done on site at regu-
lar intervals. These intervals vary among users depend-
ing on many factors: e.g. the type of protective relays
employed; the importance of the primary equipment
being protected; the user's past experience with the re-
lay, etc.
For electromechnical or static relays, maintenance test-
ing will be performed at least once a year according
to the experiences. For digital relays like MRP2, this in-
terval can be substantially longer. This is because that:
• the MRP2 relays are equipped with very wide self-
supervision functions, so that many faults in the relay
can be detected and signalized during the service.
Important: The self-supervision output relay must be
connected to a central alarm panel!
• the combined measuring functions in MRP2 relay
enable supervision the relay functions during service.
• the combined TRIP test function of the MRP2 relay al-
lows to test the relay output circuits by power system
interrupt.
A testing interval of two years for maintenance will,
therefore, be recommended.
During a maintenance testing, the relay functions in-
cluding the operating values and relay tripping charac-
teristics as well as the operating time should be tested.