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2MiCOM P921, P922 and P923Voltage and frequency relays
IntroductionPart of the new MiCOM range, theP921, P922 and P923
relaysprovide reliable and highperformance voltage and
frequencyprotection.
Their versatility of application andthe association of
protectionfunctions with automation, controland measurement
functions, as wellas maintenance reduction, providean optimal and
innovative solution.
ApplicationTwo voltage ranges are availableto cover the large
variety of controlapplications: reference voltagelevels supported
by MiCOM P921,P922 and P923 relays from 57V to 480V.
Because of the 3 independentphase overvoltage and
phaseundervoltage thresholds, MiCOMP921, P922 and P923 relays
areable to provide effective voltageprotection: a typical
applicationmight be the protection of motorsand generators. The
configurabledetection logic (AND, OR) can alsoindicate the absence
of voltage,when the undervoltage protection is used.
The 3 zero-sequence overvoltagethresholds can be applied :
to detect earth faults at the neutral point of generators,
withMiCOM P921, P922 and P923relays being insensitive to the3rd
harmonic
to detect earth faults for neutralelectrical systems which are
veryimpedant or isolated, whilstavoiding the expensive use
andinstallation of core balance CTs.
The negative sequence overvoltageprotection provided by the
MiCOMP922 and P923 relays is designedto detect unbalanced
conditions: itcould therefore be used for motorstarters, in which
any unbalancewill lead to overheating anddamage.
The MiCOM P922 and P923relays integrate 6 frequencythresholds
which are used forautomated load shedding/loadrestoration.
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Models availableMiCOM P921: voltage protectionrelays, 2 logic
inputs, 4 outputs.
MiCOM P922: voltage andfrequency protection relays, eventand
fault records, disturbancerecorder, 5 logic inputs, 8
outputcontacts.
A G version (CORTEC code option)is available to meet
thespecifications of EDF GTE 2666,types 1 and 2.
MICOM P923 : Voltage andfrequency protection relay (Plus therate
of change of frequencyelement df/dt), event and faultrecords,
disturbance recorder,5logic inputs, 8 output contacts.
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5 optoinputs
RS485Communication
Setting software
3 phases VTs
Watchdog
7 auxiliaryoutputs
Trip output
P92330 86
47
WD
RS232 RS485
27 5959N 27D
81U 81OLoadingresistor
81R
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In addition, the MiCOM P923relays provide 6 thresholds
ofinstantaneous rate of change offrequency (df/dt) or
averagemeasurements over a settable timeinterval.
These elements are suitable forsevere disturbances accelerate
theload shedding when this operation,in small step, may not be
sufficientto bring the system back to normaloperating
condition.
In order to adapt the protectionscheme to each
application,programmable logic equations areavailable and allow
thecombination of MiCOM P921,P922 and P923 internal
protectionfunctions of relays with externalsignals from other
protectiondevices on the system. Thisflexibility reduces both
externalwiring and the use of auxiliaryrelays.
The MiCOM P921, P922 andP923 relays primarily providefast and
accurate protectionfor use in numerousapplications. In addition,
theyoffer the following benefits:
protection, control,measurements and recordsin a single case,
therebyreducing the number ofdevices and the total cost
ofinstallation
clear indication of eventswhich have taken place,via explicit
messages andprogrammable LEDs on thefront panel,
increasingoperational efficiency
simple integration intocontrol systems through theuse of a large
number ofavailable standardcommunication protocols,with no
additional cost
Advantages of MiCOM P921, MiCOM P922 and MiCOM P923 relays
standardisation of cases,identical to the MiCOMP120 series
relays.
diagnostic supportfollowing a fault, throughthe use of event
recordsand disturbance records
maximum security providedby periodic self-tests
increased flexibility throughlogic inputs, outputcontacts, LEDs
andprogrammable logicequations
3 different ways of enteringthe relay settings whilstconstantly
aiming atproviding the safety, speedand simplicity required forthis
type of operation
possibility of using a"battery" box (MiCOM E1)to set the relay,
without theneed to provide anauxiliary supply
powerful and intuitiveMiCOM S1 supportsoftware designed
tominimise the need fordocumentation and training
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4Functions available
Functions ANSI Codes MiCOM P921 MiCOM P922 MiCOM P923Version S
Version G
ProtectionConfiguration depending on the number and type of
voltage transformers X X X XPhase-to-neutral or phase-to-phase
voltage protection X X X XPhase undervoltage (AND/OR logic) 27 X X
OR Logic XPhase overvoltage (AND/OR logic) 59 X X OR Logic
XSettable Hysteresis X XZero-sequence overvoltage 59N X X X
XNegative sequence overvoltage 47 X XPositive sequence undervoltage
27D X XUnder/overfrequency 81U/81O X X XRate of change of Frequency
81R XNominal operating frequency: 50 Hz/60 Hz X X X XInhibition of
voltage & frequency protection functions XInhibition of timers
(instantaneous forcing) XControlProgrammable logic equations X X X
XProgrammable logic inputs and outputs 30 X X X XFail-safe
operation XBlocking logic X X XUndervoltage Blocking XCircuit
breaker control X X X XLatching of output contacts 86 X X X
XSetting groups for protection parameters 1 2 2 2Possible
prohibition of remote setting XMeasurementsPhase-to-neutral or
phase-to-phase voltages with true RMS values X X X XResidual
voltage with true RMS value X X X XFrequency X X X XPositive and
negative sequence voltages X XRolling and peak values X XLogs and
recordsEvent records X X XFault records X X XDisturbance records X
X XFrequency Disturbance records XMonitoringMonitoring the position
of the circuit breaker X X X XData for circuit breaker maintenance
X X XCommunicationsRemote communication (RS485 port) X X X XLocal
communication (RS232 port) X X X XUser interfaceBack-lit LCD
display X X X XProgrammable LEDs X X X XPassword-protected access
(with optional transparent front cover) X X X XCompatible setting
software MiCOM S1(Windows) X X X X
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5Protection functions
Configuration depending on the VTMiCOM P921, P922 and P923relays
can be used in the followingconfigurations: "3 phase-neutral VTs"
or
"3 phase-neutral VTs and 1residual VT": The voltage protection
elementcan therefore operate either frommeasured
phase-to-neutralvoltages, or from phase-to-phasevoltages which have
beeninternally calculated by the relay.Zero-sequence
overvoltageprotection will always beavailable, the presence of
theresidual VT is designed todisplay the true RMS value of
theresidual voltage,
"3 phase-phase VTs and 1 residual VT" or "2 phase-phase VTs and
1 residual VT": The voltage protection elementcan only operate from
measuredphase-to-phase voltages. If theresidual VT is not
connected, thezero-sequence overvoltageprotection will not be
available.
The MiCOM P922-G is onlydesigned to operate with the "3
phase-neutral VTs" or "3 phase-phase VTs"configuration.
Voltage protectionFor each function listed below,
aninstantaneous signal and a time-delayed signal is available
foreach threshold.For time-delayed signals, the firstthreshold of
each function ("lowthreshold") offers the choicebetween a definite
timer and aninverse timer, to which a reset timercan be assigned.
The otherthresholds only have one definitetimer.In the case of the
MiCOM P922-G,all thresholds have definite time-delays and the only
detection logicis the "OR" logic.
Under/Overvoltage (27/59)Three thresholds are available foreach
function: each one can beindependently activated ordeactivated.
If a threshold is activated, it can beconfigured to detect: an
overvoltage on the 3
simultaneous phases (logic"AND") or on at least one of thephases
(logic "OR") for the"Overvoltage" function
an undervoltage on the 3simultaneous phases (absence ofvoltage
with the "AND" logic) oron at least one of the phases(logic "OR")
for the"Undervoltage" function
The MiCOM P923 and P923relays provide a
programmablehysteresis(drop- out / pick-up ratio) as apercentage of
the under voltageand over voltage settings values.
The MiCOM P922 provides asettable under voltage Block ofall the
protection and controlelements based on thefrequency.
Zero-sequence overvoltage(59N)Three thresholds are
available:each one can be independentlyactivated or
deactivated.Depending on the VT configuration,MiCOM P921, P922 and
P923relays will operate from the zero-sequence voltage, which
iscalculated internally, or from theresidual voltage, which is
measureddirectly.
Negative sequenceovervoltage (47) - MiCOM P922 (S version) and
P923Two thresholds are available: eachone can be independently
activatedor deactivated.This function is based on
thenegative-sequence component ofthe voltage, which is
calculatedinternally and displayed on thescreen of the front panel:
It isdesigned to detect any voltageunbalance condition.
Positive sequenceundervoltage (27D) - MiCOM P922 (S version)and
P923Two thresholds are available: Eachone can be independently
activatedor deactivated.This function is based on thepositive phase
sequencecomponent of the voltage, which iscalculated
internally.
Frequency protectionsFrequency protection functions areinhibited
from a certain level of themeasured secondary voltage(adjustable
level on G version).
Under/Overfrequency(81U/81O) - MiCOM P922and P923Six thresholds
are available: Eachone can be configured to detect anunder or
overfrequency within therange [fn - 10Hz, fn + 10Hz],where fn is
the nominal frequencyselected (50Hz or 60Hz).
A definite timer is assigned to eachthreshold.
Rate of Change of Frequency(81R)- MiCOM P923Six threshold are
available: Eachcan be configured independentlywithin the range[-10
Hz/s, +10 Hz/s]. These functions are based on thecalculation of the
instantaneousrate of change of frequency over asettable integration
time (number ofcycles).
Automation
Earth fault(V0>)
Trip&
Timer
Manualclose
(tAUX1)
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Programmable logic equations Two programmable logic
equations(AND) are available with MiCOM P921 and P922 relays. Four
programmable logic equations(AND) are available with MiCOM P923.A
pick-up timer and a drop-offtimer can be assigned to
eachequation.These equations are not defined ingraphic form, they
can thus becalculated directly from the frontpanel, thereby
avoiding the needfor dedicated software.
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Inputs/Outputs/Programmable LEDs
All logic inputs, output contacts(excluding the RL0
changeoveroutput contact, dedicated to the"relay failed" function)
and the 4LEDs of the MiCOM P921, P922and P923 relays can
beprogrammed. This affects in particular all logicsignals
(instantaneous, time-delayed) in the relays which can becombined on
the different outputcontacts and LEDs.
Blocking logicWhen MiCOM relays are used inelectrical systems,
the managementof the different protection modulesmust take
surrounding devices intoconsideration. MiCOM P921, P922and P923
relays supplyconfigurable logic inputs, which,when active, can
"freeze" theassociated protection timers andfault is still present
if the after drop-off can re-impose the initial value.
Output contact latching (86)Each output contact can beprogrammed
to be latched once thefault has cleared: The latchedcontacts can be
reset either directlyon the front panel of the relay,locally (RS232
port) or remotely(RS485 port).
Setting groups for protectionfunctionsThe MiCOM P922 and P923
relayshave two independent settinggroups, which are used to
adaptthe protection functions to differentoperating conditions. The
twogroups can be switched byactivating a dedicated logic input,or
by the operator via the frontpanel, or locally (RS232 port)
orremotely (RS485 port). Typically,these two setting groups can
beused to switch from GTE type 1.4 to GTE type 1.1 for the MiCOM
P922 G version.
The switch from one setting groupto another will only take
effect if noprotection or automation functionsare running, to
prevent unwantedtripping.
MeasurementsIn accordance with theconfiguration of the VTs
connectedto MiCOM P921, P922 and P923relays, the following values
will bedisplayed as true RMS values onthe back-lit screen:
phase-to-neutral voltages Ua, Ub, Uc
phase-to-phase voltages Uab,Ubc, Uca
residual voltage Vo
frequency.
In addition, the MiCOM P922 (S version) and P923 relayscalculate
the following valuesinternally:
positive sequence voltage
negative sequence voltage
peak values of phase-to-neutralor phase-to-phase voltages
rolling values of phase-to-neutralor phase-to-phase voltages
All measurements are availablelocally or remotely.
Logs and recordsAll event, fault and disturbancerecords are
time-stamped to 1ms bythe internal real time clock.
In the event of a loss of auxiliarypower, a lithium battery is
used tosave the records, the date and thetime. Checked at regular
intervals,the battery can be easily accessedfrom the front panel if
it has to bereplaced.
Event recordsAny change of state of logic inputs,output contacts
or protectionfunctions will be recorded in thenon-volatile memory
of the MiCOM P922 and P923 relays,with a maximum of 75 events.When
the memory is full, the oldestevents will be deleted, which
willincrease the storage capacity formore recent events.
Each event can either be displayedlocally using the MiCOM
S1support software (RS232 port) orremotely (RS485 port).
Fault recordsThe MiCOM P922 and P923 relayscan store the last 5
faults that haveoccurred in non-volatile memory.
Each record provides the followinginformation:
date and time of fault
origin of fault (undervoltage, etc.)
faulted phase(s)
magnitude of the quantity whichlead to the fault
magnitude of phase-to-neutral orphase-to-phase voltages
magnitude of the zero-sequencevoltage (if available)
All this information can be restoredlocally, using the MiCOM
S1setting software (RS232 port), orremotely (RS485 port).
Disturbance recordsFive disturbance records, eachlasting 2.5
seconds, can be storedin non-volatile memory by MiCOMP922 and P923
relays. Thesampling frequency is fixed at 32samples per cycle. The
mechanismthat triggers the recording can beconfigured:
Instantaneous signals,time-delayed signals, or activationof a
dedicated logic input.
The various recordings can berestored locally (RS232 port) or
fedback remotely (RS485 port).
Frequency disturbancerecordsOne frequency disturbance
record,lasting 20 secs can be stored innon-volatile memory by the
MiCOMP923 relay. The sampling frequencyis fixed at 1 sample per
cycle. Themechanism that triggers therecording can be
configured:instantaneous or time delayedtripping, activation of a
dedicatedlogic input or time delayed logicequation signal.
The various recordings can berestored locally (RS232 port) or
fedback remotely (RS485 port).
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Disturbance Record Analysis
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Fully WINDOWS compatible(98, NT), the MiCOM S1 settingsoftware
has been designed so thatall relay settings can be preparedin the
office ("off-line" mode) andthe configuration file created canthen
be loaded on-site.
The different information stored byeach MiCOM relay
(measurements,event records, disturbance records,parameters, etc.)
can also beretrieved by the software (storageon PC, printout of
various files, etc.)and used on-site or processed at alater
date.
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Circuit breakermonitoring and control
Monitoring the position ofthe circuit breakerThe use of logic
inputs andprogrammable LEDs enables theposition of the circuit
breaker to bedisplayed on the front panel.
Circuit breaker controlWith MiCOM P921, P922 andP923 relays, the
circuit breaker canbe controlled locally via logicinputs (AUX1 and
AUX2), withlocal or remote communication: theopening and closing
commandswill therefore activate theprogrammed output contacts.
Circuit breaker maintenance -MiCOM P922 and P923In addition to
protecting andcontrolling the electrical network,the MiCOM
P922-P923 relays willprovide preventive and curativemaintenance of
the circuit breakers.The maintenance programs can beadapted in
accordance with thedata supplied by the relay.
The MiCOM P922 and P923relays control the opening andclosing
time of the circuit breaker,and monitor the number ofoperations
carried out. An alarm istriggered as soon as the maximumopening or
closing time, or themaximum permitted number ofoperations is
exceeded.
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Hysteresis: 50mHz
I 5 Hz/T for df/dt with IT :Integration time, settable from 1 to
200
Timers:
2% or 10ms for DT
5% or 40ms for IDMT
t = TMSUUThreshold
1
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11
Technical specifications
Voltage inputs (Vn)4 voltage inputs
2 ranges available (RMS phase-phase voltage): 57-130V or
220-480V
Primary voltage:
from 0.1 to 100kV, steps of0.01kV, range 57-130V
from 220 to 480V, steps of 10V,range 220-480V
Secondary voltage:
from 57 to 130V, steps of 0.1V,range 57-130V
from 220 to 480V, steps of 10V,range 220-480V
Thermal withstand andvoltage input burdenRange 57-130V:260V
continuous300V for 10sburden: < 0.25 VA
Range 220-480V:960V continuous1300V for 10sburden: < 0.36
VA
FrequencyNominal frequency 50/60 Hz
Operating range 40/70 Hz
Auxiliary supply VauxThree ranges available
24 - 60 Vdc
48 -150 Vdc
130 - 250 Vdc / 100 - 250 Vac, 50/60 Hz
Consumption:
DC: 3W (standby)+ 0.25W per energised outputrelay
AC: 6 VA (standby)+ 0.5VA per energised output relay
Logic inputsNumber of logic inputs:2 (P921), 5 (P922 and
P923)
Configuration (P922-G) : active onlow or high level or pulse for
theinput dedicated to the change ofsetting group, active on low or
highlevel for the other inputs
Polarisation: direct voltage withinthe same range as the
auxiliaryvoltage
Response time: < 2ms
Burden: 10000 operations
Communication ports
Rear communication portConnection: multidrop (32 units)Type of
cable: twisted shielded pairLength of cable: 1000m max.Connectors:
screw terminalsLink: RS485Isolation: SELV
Front communication portConnection: peer to peerCable type:
multi-coreCable lenght: 15m max.Connectors: RS232 DTE,
9-pin,femaleLink: RS232Isolation: ELV
Backup batterySaves the date and time of event,fault and
disturbance records aswell as frequency disturbancerecord (P923
only) in the event ofan auxiliary power failure
Battery type: lithium, 1/2 AA,3.6V, 850mAh, 10-year
guarantee
CaseThe characteristics of the case areshown in figure 11
(page13).
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12
Standard tests
Environment Temperature IEC 60255-6
Storage-25C to +70C
Operation-25C to +55C
HumidityIEC 60068-2-3 56 days at 93%
RH and 40C Enclosure protection
IEC 60529 IP 52, IK 07 Vibrations IEC 60255-21-1 Response and
endurance,
class 2 Shock and bump
IEC 60255-21-11 class 1 Seismic withstand
IEC 60255-21-3, class 1
EMC compliance
89/336/EEC
Conformity to EEC EMCdirectives can be found in thetechnical
construction file.
The following genericstandards have been used as abasis for this
conformity:
EN 50081-2: 1994EN 50082-2: 1995
Product safety
73/23/EEC
Conformity to EEC low voltagedirectives.
Conformity is based on thefollowing generic safetystandards:
EN61010-1: 1993/A2: 1995EN60950: 1992/A11: 1997
Additional information Technical guide:
ref. TG1. 1530
MiCOM S1 user manual:ref. R8610
MIDOS parts catalogue:ref. R7012
Standards Dielectric withstand
IEC 60255-52 kV common mode1 kV differential mode
Impulse voltage IEC 60255-55 kV common mode1 kV differential
mode
Insulation resistance IEC 60255-5
> 100 MW High frequency disturbance
IEC 61000-4-12.5 kV common mode, class 31 kV differential mode,
class 3
Fast transient disturbance IEC 61000-4-4ANSI C37.90.1
Electrostatic dischargeIEC 61000-4-28 kV, class 4
Radiation immunityANSI C37.90.235 V/mIEC 61000-4-3 10 V/m
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22625,1
Side view, flush mounting
151,2 max.
7851.8
10,5
158168
23,6
Alldimensionsin mm.
Panel cut-out flush mountingfixing details
Relay weight (case + active part) 2,1 kg
99 4 holes 4,4 (M4 screw)
103 (20 TE)
.
C
MiCOM P921
VA = 24.50 V
177
Face view
4 holes 3,4
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Outline descriptionNumerical protection for thedetection of
voltage (P921, P922and P923) and frequency (P922and P923)
variations in a 4U draw out metal case.
A G version which meets EDF GTE2666 specifications is available
forthe P922 model.
The following functions areavailable in MiCOM P921, P922and P923
relays:
3 independent phaseovervoltage thresholds(instantaneous and
time-delayed- ANSI 59 code)
3 independent phaseundervoltage thresholds(instantaneous and
time-delayed- ANSI 27 code)
3 independent zero-sequenceovervoltage thresholds(instantaneous
and time-delayed- ANSI 59N code)
2 programmable logic equations(P921 - P922)
Programmable I/O
Relay latching (ANSI 86 code)
Display of true RMS values
An RS485 rear port compatiblewith one of the followingprotocols:
MODBUS, Courier,IEC 60870-3-105
The MiCOM P922 (S version) andMiCOM P923 relays offer
thefollowing additional functions:
2 independent negativesequence phase overvoltagethresholds
(instantaneous andtime-delayed - ANSI 47 code)
2 independent positive sequencephase undervoltage
thresholds(instantaneous and time-delayed- ANSI 27D code)
Settable Hysteresis thresholds forUndervoltage and
Overvoltagefunctions.
The MiCOM P922 relay, G version, is designed to:
instantaneously force tripping totake account of make on
powerpresent (MPP)
program output contacts 1 and 2for fail-safe operation
provide the possibility to prohibitall remote configurations
MiCOM P922 (S and G versions)and MiCOM P923 relays,therefore
integrate: 6 independent
over/underfrequency thresholds(instantaneous and time-delayed-
ANSI 81U/81O codes)
Records of the last 75 events,time-stamped to 1 ms
Data records relating to the last5 faults
Disturbance recorder withstorage of 5 records, eachlasting 2.5
seconds, 32 samplesper cycle
The MiCOM P923 relay offers thefollowing additional
functions:
6 independent rate of change offrequency thresholds - ANSI 81R
codes
1 adjustableundervoltage Blocking threshold
4 programmable logic equations
The user interface is common toMiCOM P921, P922 and P923relays
and includes the followingelements:
A 32-character alphanumericback-lit LCD display
An RS232 front port compatiblewith application software andPC
setting software
Programmable LEDs withcustomised labelling
13
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14
Relay type
User interface language options (see note 1)
Voltage relayVoltage/frequency relay (only possibility for G
application)Voltage/frequency with (df/dt)
123
Franais (choix unique pour application
G)EnglishSpanishGermanItalianRussianPolishPortugueseDutchCzechHungarian
012345678AB
Voltage inputs
57 130 V220 480 V
AB
Application
Auxiliary voltage supply
StandardEDF / GTE2666 (types 1&2)
SG
24 60Vdc 48 150Vdc 130 250Vdc/100 250Vac 50/60 Hz
AFM
Communications protocol options
Modbus (only possibility for G application) K-BUS / CourierCEI
60870-5-103
123
Note 1 : please consult us for language availability.
P92MiCOM 0 1
Informations required with order: