Woodward MRIK3 User manual
MRIK3 – Time overcurrent relay
with auto reclosing relay
(August 2006)
Manual MRIK3 (Revision New)
Woodward Manual MRIK3 GB
2 TD_MRIK3_08.06_GB_Rev.New
Woodward Governor Company reserves the right to update any portion of this publication at any time. Information
provided by Woodward Governor Company is believed to be correct and reliable. However, no responsibility is as-
sumed by Woodward Governor Company unless otherwise expressly undertaken.
© Woodward 1994-2008
Manual MRIK3 GB Woodward
TD_MRIK3_08.06_GB_Rev.New 3
Contents
1.Introduction and application ....................................................................... 6
2.Features and characteristics....................................................................... 7
3.Design ........................................................................................................... 8
3.1Connections ...................................................................................................................... 8
3.1.1Analog input circuits ...................................................................................................... 9
3.1.2AR Information input circuits ....................................................................................... 10
3.1.3Blocking input.............................................................................................................. 10
3.1.4External reset input ..................................................................................................... 10
3.1.5Output relays of MRIK3 relays .................................................................................... 10
3.1.6Fault recorder.............................................................................................................. 11
3.2LEDs ............................................................................................................................... 14
3.2.1Indication-LEDs........................................................................................................... 14
3.2.2Setting-LEDs ............................................................................................................... 14
3.3Digital Inputs ................................................................................................................... 14
3.4Low/High range of signal inputs ...................................................................................... 15
4.Working principle ....................................................................................... 16
4.1Analog circuits................................................................................................................. 16
4.2Digital circuits .................................................................................................................. 16
4.3Status descriptions.......................................................................................................... 16
4.3.1"Inactive" ..................................................................................................................... 16
4.3.2"Reclaim time" tR ........................................................................................................ 16
4.3.3"AR-ready" .................................................................................................................. 17
4.3.4"AR-starting" (dead time)............................................................................................. 17
4.3.5"AR-cycle" (auto reclosing).......................................................................................... 17
4.3.6"AR-blocked" ............................................................................................................... 17
4.3.7"Fast Trip Mode".......................................................................................................... 17
4.3.8Blocking mode............................................................................................................. 17
4.3.9Activating of AR........................................................................................................... 17
4.4Description of the status transition .................................................................................. 18
4.5Functional sequence ....................................................................................................... 19
4.5.1Switching-on MRIK3.................................................................................................... 19
4.5.2Circuit breaker manual closing .................................................................................... 19
4.5.3Circuit breaker manual open ....................................................................................... 19
4.5.4Starting AR.................................................................................................................. 19
4.5.5Unsuccessful reclosing ............................................................................................... 20
4.5.6Successful reclosing ................................................................................................... 20
4.5.7Repeated reclosing ..................................................................................................... 20
4.5.8Supervision of the circuit breaker ready information ................................................... 20
4.5.9External blocking......................................................................................................... 20
4.6Time sequence diagrams of MRIK3................................................................................ 21
4.6.1The unit is programmed for two shots, successful AR at the second shot .................. 21
4.6.2The unit is programmed for two shots, unsuccessful AR ............................................ 22
4.6.3Manual closing of the circuit breaker to faulty lines..................................................... 22
4.6.4Unsuccessful AR......................................................................................................... 23
5.Operations and settings ............................................................................ 24
5.1Display ............................................................................................................................ 24
5.2Setting procedure............................................................................................................ 26
5.3Systemparameter............................................................................................................ 26
5.3.1Display of measuring values as primary quantities (Iprim phase).................................. 26
5.3.2Display of earth current as primary quantity (Iprim earth).............................................. 26
5.3.3Nominal frequency ...................................................................................................... 26
5.3.4Display of the activation storage (FLSH/NOFL) .......................................................... 26
5.3.5Parameter switch/external triggering of the fault recorder........................................... 27
5.4Parameter protection....................................................................................................... 28
5.4.1Pickup current for phase over current element (I>) ..................................................... 28
5.4.2Time current characteristics for phase over current element (I> + CHAR).................. 28
5.4.3Trip delay or time multiplier for phase over current element (tI>)................................. 28
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5.4.4Reset setting for inverse time tripping characteristics in the phase current path......... 28
5.4.5Current setting for high set element (I>>).................................................................... 29
5.4.6Trip delay for high set element (tI>>)........................................................................... 29
5.4.7Pickup current for earth fault element (IE>) .................................................................. 29
5.4.8WARN/TRIP changeover............................................................................................. 29
5.4.9Time current characteristics for earth fault element (CHAR IE) ................................... 29
5.4.10Trip delay or time multiplier for earth fault element (tIE>>) ........................................ 29
5.4.11IE> Tripping is blocked at IE>>Alarm ...................................................................... 29
5.4.12Current setting for high set element of earth fault supervision (IE>>)........................ 30
5.4.13Trip delay for high set element of earth fault supervision (tIE>>) ............................... 30
5.4.14Parameters auto reclosing Number of AR-SHOTS ................................................. 30
5.4.15Fault time (tF) ........................................................................................................... 30
5.4.16Dead time (tD) ......................................................................................................... 30
5.4.17Close impulse time (tCI)............................................................................................ 30
5.4.18Reclaim time (tR)...................................................................................................... 30
5.4.19Fault time activation................................................................................................. 30
5.4.20Block/Trip - time....................................................................................................... 31
5.4.21Circuit breaker failure protection tCBFP...................................................................... 31
5.4.22Adjustment of the slave address.............................................................................. 31
5.4.23Setting of Baud-rate (applies for Modbus Protocol only) ......................................... 31
5.4.24Setting of parity (applies for Modbus Protocol only) ................................................ 31
5.5Fault recorder .................................................................................................................. 32
5.5.1Number of the fault recordings .................................................................................... 32
5.5.2Adjustment of trigger occurrences............................................................................... 32
5.5.3Pre-trigger time (Tpre)................................................................................................... 32
5.6Adjustment of the clock ................................................................................................... 32
5.7Additional functions ......................................................................................................... 33
5.7.1Blocking the protection functions, assignment of the output relays and
AR - functions .............................................................................................................. 33
5.8Indication of measuring and fault values ......................................................................... 37
5.8.1Indication of measuring values .................................................................................... 37
5.8.2Unit of the measuring values displayed....................................................................... 37
5.8.3Indication of fault data ................................................................................................. 37
5.9Fault memory .................................................................................................................. 38
5.10Reset ............................................................................................................................... 39
5.10.1Erasure of fault storage ........................................................................................... 39
6.Relay testing and commissioning ............................................................ 40
6.1Power-On ........................................................................................................................ 40
6.2Testing the output relays and LEDs ................................................................................ 40
6.3Checking the set values .................................................................................................. 40
6.4Secondary injection test .................................................................................................. 41
6.4.1Test equipment............................................................................................................ 41
6.4.2Example of test circuit for MRIK3 relays...................................................................... 41
6.4.3Checking the input circuits and measured values ....................................................... 42
6.4.4Checking the operating and resetting values of the relay............................................ 42
6.4.5Checking the relay operating time ............................................................................... 42
6.4.6Checking the high set element of the relay.................................................................. 42
6.4.7Checking the auto reclosing function........................................................................... 43
6.4.8Checking the circuit breaker position (A2/A7 and A2/A5)............................................ 43
6.4.9Checking the AR-blocking input (A2/A3) ..................................................................... 43
6.4.10Checking the external blocking and reset functions ................................................ 44
6.4.11Testing the external blocking with Block/Trip function ............................................. 44
6.4.12Test of the CB failure protection .............................................................................. 44
6.5injection test .................................................................................................................... 45
6.6Maintenance.................................................................................................................... 45
7.Technical data ............................................................................................ 46
7.1Measuring input circuits................................................................................................... 46
7.2Common data.................................................................................................................. 46
7.3Setting ranges and steps................................................................................................. 47
7.3.1Time overcurrent protection......................................................................................... 47
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7.3.2Earth fault protection ................................................................................................... 47
7.3.3Inverse time over current protection relay ................................................................... 48
7.3.4Inverse time characteristics......................................................................................... 49
7.4Parameter ....................................................................................................................... 53
7.5Design standard .............................................................................................................. 54
8.Order form................................................................................................... 55
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1. Introduction and application
The MRlK1 digital multifunctional relay is a universal time over current and earth fault protection
device with integrated auto reclosing relay intended for use in medium-voltage systems, either with
an isolated/compensated neutral point or for net-works with a solidly earthed/resistance-earthed
neutral point.
In transmission line networks more than 70% of the occurring faults are transient (electric arcs ex-
tinguish, branches are falling on the overhead lines etc.)
With the application of the automatic reclosing (AR) together with protection relays, many electric
arcs are extinguished through temporary interruption of the energy supply.
Without utilizing the automatic reclosing (AR) power supply interruptions would occur quite fre-
quently.
Statistics have shown that yet part of the faults remain after the first fast AR can be cleared with a
longer 2nd AR interval.
The digital multi-shot, three phase auto reclosing relay MRIK3 fulfills these requirements for use on
medium voltage transmission or distribution systems, by 4-element AR with variable adjustable
dead times.
Important:
For additional common data of all MR-relays please refer to manual "MR - Digital Multifunctional re-
lays".
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2. Features and characteristics
•Digital filtering of the measured values by using discrete Fourier analysis to suppress the
high frequency harmonics and DC components induced by faults or system operations,
•two parameter sets,
•selectable protective functions between:
- definite time over current relay or
- inverse time over current relay,
•selectable inverse time characteristics according to IEC 255-4:
- Normal Inverse (Type A)
- Very Inverse (Type B)
- Extremely Inverse (Type C
- Special characteristics,
•reset setting for inverse time characteristics selectable,
•high set over current unit with instantaneous or de-finite time function,
•two-element (low and high set) over current relay for both phase and earth faults
independent from each other,
•circuit breaker failure protection,
•4-element AR with Fast-Trip Mode,
•adjustable timer for fault time, dead time, close impulse time and reclaim time,
•external blocking and blocking release of AR,
•optical indications of the AR functional sequence and the AR results,
•external control through optically isolated inputs,
•number of auto reclosing, adjustable from 1 to 4,
•display of measuring values as primary quantities,
•blocking e.g. of high set element (e.g. for selective fault detection through minor
over current protection units after unsuccessful AR),
•free assignment of output relays,
•free assignment of protective function for every reclosing separately adjustable,
•blocking the protection function or Fast-Trip-tripping for a selective switch off before and
after each AR separately adjustable,
•suppression of indication after an activation (LED flash),
•storage of trip values and switching-off time (tCBFP) of 5 fault occurrences (fail-safe of
voltage),
•recording of up to eight fault occurrences with time stamp,
•serial data exchange via RS485 interface possible; alternatively with SEG RS485
Pro-Open Data Protocol or Modbus Protocol,
•display of date and time
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3. Design
3.1 Connections
Figure 3.1: Connections MRIK3-I
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Figure 3.2: Connections MRIK3-IE
3.1.1 Analog input circuits
The protection unit receives the analog input signals of the phase currents IL1 (B3-B4), IL2 (B5-B6),
IL3 B7-B8) and the current IE(B1-B2), each via separate input transformers.
The constantly detected current measuring values are galvanic ally decoupled, filtered and finally
fed to the analog/digital converter.
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3.1.2 AR Information input circuits
With the aid of information inputs unit MRIK3 decides whether and when auto-reclosing may take
place:
Circuit breaker position (A7)
With input A7 the position of C.B. can be supervised.
When the circuit breaker is closed the auxiliary voltage is connected to input A7.
Circuit breaker energy (e.g. motor-wound spring-closed breakers) (A5)
Because the circuit breaker needs a certain time between two reclosing-attempts in order to close
again, the ready signal of the C.B. (auxiliary voltage at A5) is checked before a new auto reclosing
takes place. (see also para. 4.5.8)
External blocking input (A3)
The unit is blocked when applying voltage to A3.
Common point of the inputs (A2)
All listed inputs have a common connection point for L- or N.
3.1.3 Blocking input
The protection functions adjusted be-fore will be blocked if an auxiliary voltage is applied to
(terminals) D8/E8 (refer to chapter 5.7.1).
3.1.4 External reset input
Please refer to chapter 5.10.
3.1.5 Output relays of MRIK3 relays
Two relays are equipped with two change-over contacts and three relays with each one change-
over contact for alarm. Apart from the relay for self-supervision, all protective functions can be op-
tionally 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
•Relay 5: Self-supervision C7, D7, E7
All trip and alarm relays are working current relays, the relay for self supervision is an idle current
relay.
The output relays can be assigned to the tripping functions as required.
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3.1.6 Fault recorder
The MRIK3 has a fault value recorder which records the measured analog values as instantaneous
values. The instantaneous values
iL1, iL2, iL3, iE, (iUe)*,
are scanned at a raster of 1.25 ms (at 50 Hz) and 1.041 ms (at 60 Hz) and saved in a cyclic buffer.
It is possible to store 1 - 8 fault occurrences with a total recording time of 16 s (with 50 Hz) and
13.33 s (with 60 Hz) per channel. (see chapter 5.5.1)
Storage division
Independent of the recording time, the entire storage capacity can be divided into several cases of
disturbance with a shorter recording time each. In addition, the deletion behavior of the fault re-
corder can be influenced.
No writing over
If 2, 4 or 8 recordings are chosen, the complete memory is divided into the relevant number of par-
tial segments. If this max. number of fault event has been exceeded, the fault recorder block any
further recordings in order to prevent that the stored data are written over. After the data have been
read and deleted, the recorder to ready again for further action.
Writing over
If 1, 3 or 7 recordings are chosen, the relevant number of partial segments is reserved in the com-
plete memory. If the memory is full, a new recording will always write over the oldest one.
The memory part of the fault recorder is designed as circulating storage. In this example 7 fault
records can be stored (written over).
Figure 3.3: Division of the memory into 8 segments, for example
Memory space 6 to 4 is occupied.
Memory space 5 is currently being written in
Since memory spaces 6, 7 and 8 are occupied, this example shows that the memory has been as-
signed more than eight recordings. This means that No. 6 is the oldest fault recording and No. 4
the most recent one.
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Figure 3.4: Basic set-up of the fault recorder
Each memory segment has a specified storage time which permits setting of a time prior to the
trigger event. Via the interface RS485 the data can be read and processed by means of a PC with
HTL/PL-Soft4. The data is graphically edited and displayed. Bi-nary tracks are recorded as well,
e.g. activation and trip.
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Figure 3.5: Front panel MRIK3-I
Figure 3.6: Front panel MRIK3-IE
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3.2 LEDs
Five pushbuttons for control and/or adjustment and up to 21 LEDs are on the front plate of unit
MRIK3. The LEDs on the left side of the display indicate the status, fault messages and AR- re-
sults. The function of the respective LED is indicated by the legend above the LED.
The LEDs on the left side beneath the <SELECT/RESET> pushbutton are provided for adjust-
ments, their functions are shown with a legend on the right or left side of the LED.
3.2.1 Indication-LEDs
L1, L2, L3, E: Phase or earth current
O→I green: AR successful; red: AR unsuccessful
OK: AR ready (Does not light: AR inactive)
AR: AR status
CB: Circuit breaker on
RS: Setting slave address
3.2.2 Setting-LEDs
P2: Two parameter sets
I>: green, pickup value phase current
tI>: red, trip delay / time multiplier phase current
I>>: green pickup value phase current
tI>>: red, trip delay phase current
IE>: green, pickup value earth current
tIE>: red, trip delay / time multiplier earth current
IE>>: green, pickup value earth current
tIE>>: red, trip delay earth current
CHAR green, tripping characteristic phase and earth path
tRST: red, reset time phase and earth
SHOT: green, number of the reclosing attempts
tF: red, Fault time
tD1: green, Dead time for the first reclosing attempt
tD2: red, Dead time for the second reclosing attempt
tD3: green, Dead time for the third reclosing attempt
tD4: red, Dead time for the fourth reclosing attempt
tC1: green, Close impulse time
tR: red, Reclaim time
C.B. : Time delay of circuit breaker failure protection
3.3 Digital Inputs
The MRIK3 has 5 digital inputs with fixed functions. All inputs have a common reference point :
Terminal D8. (See Chapter 3.1)
No Terminal Function Coding Plug
1 C8 External reset 2
2 E8 External blocking 1
3 A3 AR-Blocking 5
4 A5 CB-Ready 6
5 A7 CB-status 7
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3.4 Low/High range of signal inputs
The MRIK3 has a wide-range power sup-ply unit allowing to choose a suit-able supply voltage. The
operating threshold of the signal inputs, how-ever, has to be defined by taking the supply voltage
into account. The following two different operating thresholds can be adjusted:
Range Plug U
not active U
active
Low Plugged in <= 8V >= 10V
High Open <= 60V >= 80V
Figure 3.7: Code jumper for MRIK3 relays
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4. Working principle
4.1 Analog circuits
The incoming currents from the main current transformers on the protected object are converted to
voltage signals in proportion to the currents via the input transformers and bur-den. The noise sig-
nals caused by inductive and capacitive coupling are suppressed by an analog R-C filter circuit.
The analog voltage signals are fed to the A/D-converter of the microprocessor and transformed to
digital signals through Sample- and Hold-circuits. The analog signals are sampled at 50 Hz (60 Hz)
with a sampling frequency of 800 Hz (960 Hz), namely, a sampling rate of 1.25 ms (1.04 ms) for
every measuring quantity. (16 scans per periode).
4.2 Digital circuits
The essential part of the MRIK3 relay is a powerful microcontroller. All of the operations, from the
analog digital conversion to the relay trip decision, are carried out by the micro-controller digitally.
The relay pro-gram is located in an EPROM (Electrically-Programmable-Read-Only-Memory). With
this program the CPU of the microcontroller calculates the three phase currents and ground current
in order to detect a possible fault situation in the protected object.
For the calculation of the current value an efficient digital filter based on the Fourier Transformation
(DFFT - Discrete Fast Fourier Transformation) is applied to suppress high frequency harmonics
and DC components caused by fault-induced transients or other system disturbances.
The calculated actual current values are compared with the relay settings. If a phase current ex-
ceeds the pickup value, an alarm is given and after the set trip delay has elapsed, the correspond-
ing trip relay is activated.
The relay setting values for all parameters are stored in a parameter memory (EEPROM - Electri-
cally Erasable Programmable Read-only Memory), so that the actual relay settings cannot be lost,
even if the power supply is interrupted.
The microprocessor is supervised by a built-in "watchdog" timer. In case of a failure the watchdog
timer resets the microprocessor and gives an alarm signal, via the output relay "self supervision".
4.3 Status descriptions
Reaction to protection events is possible at any time unless blocking is expressly desired (refer to
3.1.3). In the inactive and blocked state auto reclosing is not possible.
For the explanation of the functional sequence the following six status transitions are defined.
4.3.1 "Inactive"
The relay is in "inactive" status if one of the following conditions is fulfilled:
•The circuit breaker is in position "OFF",
•the unit is in "blocked" status,
•the unit is not in "starting/cycle" status
4.3.2 "Reclaim time" tR
The relay is in "reclaim time" status (tR) when the reclaim time
•has not yet expired or
•not interrupted by other incidents.
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4.3.3 "AR-ready"
The relay is in position "AR-ready" status when the following conditions are fulfilled:
•The circuit breaker is in position "ON",
•the reclaim time has expired,
•the unit is not in "blocked" status,
•the unit is not in "starting cycle" status.
Only in "AR-ready" status a reaction of the AR-unit to the protection incidents is possible!
4.3.4 "AR-starting" (dead time)
In "AR-starting" status the start conditions for an automatic reclosing by means of the protection
commands and the circuit breaker position are checked.
4.3.5 "AR-cycle" (auto reclosing)
The reclosing commands are carried out in "AR-cycle" status by means of the conditions and the
presetting. The results (AR successful or unsuccessful) are evaluated accordingly.
4.3.6 "AR-blocked"
Unit MRIK3 changes immediately to "AR-blocked" status when an external or internal blocking
signal (A2-A3) exists. No auto reclosing is possible in "AR-blocked" status.
4.3.7 "Fast Trip Mode"
By way of the function "Assignment of the AR functions" it is possible to activate or deactivate a
Fast Trip function for each AR stage and for each protective function. This is applicable for tripping
before the 1st AR up to tripping after the last AR.
4.3.8 Blocking mode
By way of the function "Assignment of the AR functions" it is possible to activate or deactivate a
protection function for each AR stage. This is applicable for tripping before the 1st AR up to tripping
after the last AR.
4.3.9 Activating of AR
Prior to every AR it is possible to stipulate which kind of tripping (I> or I>>, etc.) will lead to auto-
matic reclosing. This can be separately fixed for each AR stage.
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4.4 Description of the status transition
AR-status transition matrix
inactive reclaim
time
ready starting
(dead time)
cycle (auto-
reclosing)
blocked
inactive C.B maual
ON
external
blocking
signal
reclaim
time
reclaim
time ex-
pired
external
blocking
signal
ready C.B.
OFF
protection
energized
and/or tripped
and C.B.-
energy OK
external
blocking
signal
starting Starting
conditions
not fulfilled
start signal
interrupted
start condi-
tions fulfilled
(fault time,
C.B. OFF etc.)
external
blocking
signal
cycle AWE takes
place
external or
internal
blocking
signal
blocked external
reset of
blocking
Table 4.1: No status transition possible
From Table 4.1 you can detect what status transitions of MRIK3 are possible. When the unit is for
instance in "cycle" status (see also para. 4.3) only two status transitions are possible:
•status transition to "ready"-status when the auto reclosing takes place
•status transition to "blocked" status by external or internal blocking.
The grey shaded sections indicate that no transition is possible.
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4.5 Functional sequence
4.5.1 Switching-on MRIK3
Is the C.B. to be supervised in OFF position while “switching ON” the MRIK3, the unit changes into
"inactive" status when applying the auxiliary voltage. The LED "CB" on the front plate remains dark.
The unit is not ready for auto reclosing. If, however, the C.B. is in “ON” position when applying the
auxiliary voltage, the unit changes into "reclaim time"-status and remains blocked during this period
(from 1 s to 300 s adjustable). This is indicated at the unit by LED tR. After expiration of the reclaim
time the unit changes to "ready" status and is then ready for auto reclosing. LED "CB" signalizes
this status. In case unit MRIK3 is in "blocked" status before auxiliary voltage failure occurred, this
condition remains also after recurrence of auxiliary voltage.
The LED CB shows the position of the C.B.
4.5.2 Circuit breaker manual closing
If the circuit breaker is closed manually to a faultless line, first the unit remains blocked during the
reclaim time (adjustable 1 - 300 s) and then changes to "ready" status. If the circuit breaker is
closed manually to a faulty line (e.g. short circuit), no AR follows. Unit MRIK3 remains in "inactive"
status after protection tripping. This is indicated on the display by „MANU“.
4.5.3 Circuit breaker manual open
When switching off the circuit breaker manually the unit changes at once without time delay from
"ready" status into "inactive" status. Auto reclosing is not possible.
The LED CB extinguishes.
4.5.4 Starting AR
When the information "protection energized" and "protection tripping" is applied, the unit changes
from "ready" status to "starting" status. The LED "AR" lights up. The "starting" status begins with
the start of a fault timer (tF from 0.1 s to 2.0 s adjustable). The LED tF lights up red. A tripping timer
(set at 0.2 s) is started when the mains protection tripping command takes place before expiration
of the set fault time. (C.B. must be tripped within this time). The "start conditions not fulfilled" is eva-
luated and the MRIK3 is locked for the duration of the reclaim time when there is a time dif-ference
between mains protection-energized and tripping, which is larger than the set "fault time". The LED
tF flashes red. If the OFF-signal of the C.B. appears before expiration of the tripping timer, it is eva-
luated as "start condition fulfilled" and the unit changes over to "cycle" status. The LED tF extin-
guishes. If the OFF-signal does not appear, how-ever, before expiration of the trip-ping timer, it will
be evaluated as "start condition not fulfilled" and the unit changes to „inactive“ status. The LED CB
flashes and the Display shows „CB??“.
Tripping timer: Time from the beginning of the tripping command until receiving of the C.B. check-
back signal.
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4.5.5 Unsuccessful reclosing
After the start condition has been fulfilled the unit changes to "starting" status. Now the dead time
tD is started. The corresponding LED flashes. Unit MRIK3 can be programmed for reclosing of one
to four times. For each reclosing a dead time has to be set (tD1 to tD4). When the dead time has ex-
pired and also the other re-closing conditions have been fulfilled, the reclosing command is given to
the circuit breaker. The reclosing command remains either as long as the ON-signal from the circuit
breaker appears or the close-impuls-timer (tCL) has expired.
The LED tCL lights up for the duration of the close impulse. When the CB-ON message occurs, the
LED tCL extinguishes. After expiration of the ON impulse timer the LED starts flashing and the dis-
play shows "CB??"
In the last case a failure of the circuit breaker is subjected. With the beginning of the reclosing
command the reclaim timer is started. When a new “OFF-signal” of the circuit breaker appears
within the re-claim time and after the last permissible AR, an unsuccessful reclosing will be de-
tected. The LED 0→I lights up red and the display shows „OPEN“. Then the unit quits the "cycle"
status and changes to the "inactive" status. Simultaneously a relay can be activated which indi-
cates unsuccessful auto reclosing.
4.5.6 Successful reclosing
If there is no “OFF-signal” of the circuit breaker and no protection tripping within the reclaim time a
successful reclosing will be detected.
During the reclaim time the display shows „CLOS“ and the LED 0→I lights up green.
The unit now quits the "cycle" status, changes over into the "ready" status and is ready for the next
re-closing. The LED AR extinguishes and the CB LED lights up. The display shows „SEG“.
4.5.7 Repeated reclosing
Is the MRIK3 programmed for more than single reclosing a further dead time is started after a new
“OFF-signal” from the circuit breaker has appeared. After expiration of this dead time a new reclos-
ing command follows.
4.5.8 Supervision of the circuit breaker ready information
Because the supervising unit of the circuit breaker energy store operates often after the first fast
switch off (see also para. 3.1.2), the signal "C.B. not AR-ready" is not evaluated anymore after an
introduced reclosing. The C.B. ready information is checked before an introduced AR for further
ARs. There will be a reclosing when the "circuit breaker ready" had been given before the begin of
the reclosing cycle. If not, the LED CB flashes and the display shows „S/E?“.
4.5.9 External blocking
The AR-relay is blocked if the the external AR-block input is activated.
When the reclosing shot is set to „EXIT“, the MRIK3 can also be blocked at site. (see chapter
5.4.14)
Table of contents
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