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.