ABB SPAD 330 C User manual

1
ASEABROWN BOVERI
ABB Relays
34 SPAD 4 EN1 C
1992 - 10 - 27
Written
Checked
Approved
Differential relay
SPAD 330 C
Three-phase biased differential relay
fortheprotectionofpowertransformers
and generator-transformer units.
Matching of the power transformer
vectorgroupwithDlLswitchesandthe
electronics. No intermediate current
transformers are needed.
The transforming ratio errors of the
C.T.s separately correctable on the HV
and LV side of the power transformer.
Separately adjustable differential
current high-set instantaneous stage.
Stabilizedoperatingprincipleprevents
spurious function on faults occurring
outside the area of protection.
Blocking function, for prevention of
spurious operations caused by con-
nection inrush currents, based on the
occurrence of the second harmonic.
Local display of measured and set
values on relay front panel.
Continuous self-supervision of the
electronic circuitry and the operation
of the microprocessor.
Features
C

2
Features ..........................................................................................................1
Application.......................................................................................................2
Description of function.....................................................................................2
Connection diagram ........................................................................................5
Connections ....................................................................................................6
Intermodular control signals ............................................................................7
Signal abbreviations........................................................................................7
Output relay module........................................................................................8
Auxiliary power module ...................................................................................9
Applications...................................................................................................10
Technical data...............................................................................................15
Spare parts....................................................................................................16
Information required with order .....................................................................17
The complete User’s Manual for the differential relay SPAD 330 C is composed of the
following partial documents:
General differential relay description 34 SPAD 4 EN 1
General characteristics of C-type relay modules 34 SPC 2 EN 1
Differential relay module 34 SPCD 1 EN 1
Instructions for mounting and maintenance of relays
of the SPA-300 series 34 SPA 11 EN 1
Contents
Thedifferential relay SPAD 330Cisdesigned
to be used as a fast interwinding short-circuit
and interturn fault protection for two-winding
powertransformersandpowerplantgenerator-
Application transformerunits.Therelayisalsoadoptedfor
three-windingpowertransformersprovidedthat
the power transformer is characterized by a
unidirectional power flow.
The differential relay compares the phase
currentson either side of theprotectedobject.
If the amplitude or phase angle difference of
the currents, or both, exceed the threshold
value setting, the relay operates. The current
transformer secondary currents measured on
either side of the protected object are desig-
natedI1andI2.Undernormalserviceconditions,
that is when there is no fault in the protected
area,theI1currentisequaltotheI2currentand
the differential current Id= 0, expression 1.
Id = I1- I2(1)
In practice the differential current Iddeviates
fromzeroalsoundernormalserviceconditions.
When protecting power transformers, differ-
ential currents are caused by inaccuracies of
the current transformers, changes in the tap-
changerposition,no-loadcurrentofthepower
Description of
function transformer and temporarily by transformer connectioninrushcurrents.Asthetransformer
load current increases, the differential current
causedbythecurrenttransformerinaccuracies
and the tap-changer grows in the same
proportionastheloadcurrent.Atshort-circuits
occurringoutsidetheprotectedarea,andwhen
motors are started, the load current may grow
high enough to cause partial saturation of the
current transformers. In such a case the
differentialcurrent may grow tomanytensper
centoftheloadcurrent.Becauseofthesefacts
the operation of the differential relay has to be
stabilized to the load current. The higher the
load current in a biased differential relay, the
higher the differential current is required to
cause a relay operation. The bias current Ibof
the relay is determined by expression 2:
lb= ( I1+ I2) /2 (2)

3
Theeffectofthebiasfunctionontheoperation
of the relay is graphically illustrated by the
characteristic curve presented in Fig. 2.
The differential relay has two adjustable
parameters,thebasicsettingpofthedifferential
current and the starting ratio setting s. Using
the designations in Fig. 2 the settings p and s
can be specified as follows:
p = Id1 / In(3)
s = Id2 / Ib2 (4)
The slope of the characteristic curve varies in
the different sections:
Partial range 1
IntherangeIb=0…0.5xInthedifferentialcurrent
required for the relay to operate is constant.
The value of the differential current is equal to
thebasicsettingvaluepoftherelay.Thebasic
settingprimarilyallows fordifferentialcurrents
caused by a no-load situation of the power
transformer, but it may also affect the whole
levelofthecharacteristiccurve.Atratedvoltage
the no-load losses of the power transformer
canbe expressed astenthsof a per centonly.
But if the voltage of the power transformer
suddenly rises due to an operational disturb-
ance,themagnetizingcurrentofthetransformer
consequently rises. Normally, the magnetic
flux density of the power transformer is rather
highatratedvoltage,andthenavoltageriseof
a couple per cents causes the magnetizing
current to rise by several tens of units of per
cent.Thisfactisconsideredinthebasicsetting.
Partial range 2
Therangebetween0.5xIn<Ib<2.5xIniscalled
the influence area of the starting ratio s. By
setting the starting ratio, it is possible to
influence the slope of the characteristic curve
in this area, i.e. how big a change in the
differentialcurrent,inrelationtotheloadcurrent
change, is required for tripping. The starting
ratiomakesallowanceforerrorsofthecurrent
transformers and changes of the tap-changer
position. When using current transformers of
the10Paccuracyclass,thecurrenterrorinthe
rated current range does not exceed 3 %.
Hence the errors caused by the current
transformers may be in the class of 3+3 % =
6 % at the most.
Thestartingratiomustnotbetoohigh,because
thesensitivityofthedifferentialrelaytointerturn
faults of the power transformer depends
primarily on the starting ratio.
Partial range 3
At high bias current values, Ib> 2.5 x In, the
characteristic curve has a constant slope,
approx. 100 %. This means that the increase
in the differential current required for relay to
tripping equals to the increase in the corre-
sponding bias current.
Theactualcharacteristiccurveandthesetting
range of the biased differential relay are
illustrated in Fig. 2. The setting values can be
adjusted within the shaded area.
Fig.1. Theoretical characteristic curve of a biased differential relay.
12 3
Id
In
2
1
Id1
Ib2
Id2
Ib3
Id3
12345 Ib
In
B

4
Inpowertransformerprotectionthestabilization
of the operation with regard to the restraint
current is not enough to ensure a correct
operation of the relay under all operation
conditions .
Theconnectionofthepowertransformertothe
network causes a connection inrush current,
theamplitudeofwhichmaybe manytimesthe
magnitude of rated current and which may
have a half-time of up to several seconds. To
the differential relay this connection inrush
current represents pure differential current,
and would make the relay operate almost
always when the transformer is connected to
the network. To eliminate the effect of the
connectioninrushcurrentthedifferentialrelay
is provided with a blocking function, the
operationofwhichisbasedontheoccurrence
of a second harmonic component of the
differential current. The second harmonic
component in the connection inrush current
mayvaryintherange12…100%.Theoperation
of the differential relay is blocked when the
secondharmoniccomponentofthecurrenton
one of the phases exceeds the set blocking
level. The blocking level is adjustable within
the range 10…20 % of the differential current.
The unintended operations caused by partial
saturation of the current transformers are
prevented not only through stabilization. The
unintended operations are also prevented in
such a way that the measurement of the
differential current and a possible tripping
decision are based only on current samples
measured during the quarter-cycle following
thezerocrossing oftheHVandLV sidephase
currents. This lowers the requirements on the
current reproduction capability of the current
transformers.
The differential relay is also provided with a
high-setinstantaneousstage.Thesettingrange
ofthehigh-set stageis20…30x In.Ithasbeen
selected so that the relay does not operate on
thehigh-setstageuntilhighabovethehighest
unsymmetrical connection inrush current
levels.Asthebiascurrentgoesbelowapprox.
33%ofthedifferentialcurrentthesettingvalue
of the high-set stage is automatically halved,
cause under such circumstances a fault must
existwithintheprotectedarea.Theloadcurrent
hasnostabilizingeffectontheoperationofthe
high-set stage.
Intransformerprotectionithaspreviouslybeen
necessary to use intermediate current trans-
formers in association with differential relays,
inordertomatchthevectorgroupandthesec-
ondarycurrentsofthemaincurrenttransform-
ers. In most cases, when using SPAD 330C,
the intermediate transformers can be omitted,
because the matching can be made by using
theswitchesandthesettingknobsonthefront
panel of the relay modules.
Fig. 2. Setting range of the characteristic curve of the biased differential relay SPAD 330 C.
4.0
3.0
2.0
1.0
0.00.0 1.0 2.0 3.0 4.0 5.0 6.0
Curve p/% s/%
1 50 50
2 20 10
1.
2.
0.5
0.5 2.5
Id
In
Ib
In

5
Fig. 3. Block schematic diagram of the biased differential relay SPAD 330 C.
Connection
diagram
Uaux Auxiliary voltage
A, E Output relays
I RF Self-supervision
Ul Differential relay module of L1 phase SPCD 3C21
U2 Differential relay module of L2 phase SPCD 3C22
U3 Differential relay module of L3 phase SPCD 3C23
U4 Output relay module SPTR 5B4
U5 Power supply module SPGU 240A1, SPGU 48B2
U6 Input/output module SPTE 6B3
P1
S2
P2 P1 P2
S1 S2
S1
L1
L2
L3
SPAD 330 C
SPAD 330 C

6
Thebiased differential relaySPAD330 C has
the following inputs and outputs.
Connections
Terminal No. Function
1-2 Phase current IL1 of the HV side (5 A)
1-3 Phase current IL1 of the HV side (1 A)
4-5 Phase current IL2 of the HV side (5 A)
4-6 Phase current IL2 of the HV side (1 A)
7-8 Phase current IL3 of the HV side (5 A)
7-9 Phase current IL3 of the HV side (1 A)
13-14 Phase current IL1 of the LV side (5 A)
13-15 Phase current IL1 of the LV side (1 A)
16-17 Phase current IL2 of the LV side (5 A)
16-18 Phase current IL2 of the LV side (1 A)
19-20 Phase current IL3 of the LV side (5 A)
19-21 Phase current IL3 of the LV side (1 A)
61-62 Auxiliary voltage supply. The positive lead of the dc supply is
to be connected to terminal 61. The auxiliary voltage range is
marked on the front panel.
63 Protective earth
65-66 CB tripping contact
68-69 CB tripping contact
73-74-75 Signalling contact
76-77-78 Signalling contact
70-71-72 Self-supervision alarm contact. Under normal service conditions
the relay is energized and the contact gap 70-72 is closed.
When a fault occurs or the auxiliary voltage is interrupted,
the contact gap 71-72 closes.
The differential relay SPAD 330 C is provided
forbeingconnectedtothefibre-opticSPAdata
bus. The connection is performed by using a
SPA-ZCseriesbus interface module, which is
tobeattachedtothe9-poleD-typesubminiature
connector located in the centre of the rear
paneloftherelayunit.Thescrewsrequiredare
included in the delivery of the optional bus
interface module. The terminals of the fibre-
optic cables are connected to the counter
terminals Rx and Tx on the bus interface
module.Thefibre-optic cables are linked from
one protection relay to the other and to the
control data communicator. The type desig-
nations of the bus interface modules and
fibre-optic cables are found in the document
34 SPA 12 EN1 “Characteristics of fibre-optic
cables and instructions for mounting”.
Fig. 4. Rear view of the biased differential relay SPAD 330 C.

7
Intermodular
control signals
Fig. 5. The control signals routed between the functional modules of the differential relay. The
secondharmonicblockingsignalBSOUTgeneratedbyanyrelayphasemodulealsoblocksthe
other phase modules.
In connection and block diagrams the signal
abbreviations have been derived from the
Signal
abbreviations English names of the signals, as follows:
Abbreviation English equivalent
I1
I2
IdDifferential current
IbBias (restraint) current
InRated current
I2f 2nd harmonic or
Ihr Harmonic restraint current
TS Trip signal
BS Blocking signal
IRF Internal relay fault
ENA Enable
Rx Receiver channel
Tx Transmitter channel
R Reset
S&R Step and Reset
STRÖMBERG
SPAD 330 C
I2f>
Id>
U1
SPCD3C21
I2f>
Id>
U2
SPCD3C22
I2f>
Id>
U3
SPCD3C23
TS
TS
TS
ENA
ENA
ENA
BS IN
BS OUT
BS IN
BS OUT
BS OUT
BS IN
1
A
U4
SPTR5B4

8
The output relay module SPTR 5B4 of the
biaseddifferentialrelaySPAD330Cislocated
togetherwiththepowersupplymodule,behind
thesystem front panel,whichisfixed with four
cross-slottedscrews.Theoutputrelaymodule
contains the output relays and the control
circuitsoftheserelays.Theoutputrelaymodule
forms a separate, withdrawable relay module.
Output relay
module The incoming and outgoing signals of the output relay module are firmly related to the
modulelocationsof therelaycase.Theoutput
signals from each module location are
individually routed to the output relay module.
Therefore,itisimportantthattherelaymodules
are plugged into the relay case in the order
illustratedinthefigureonPage1.Thisensures
thatthefunctionoftherelaycorrespondstothe
connection diagram of the relay unit.
Fig. 6. Block diagram of output relay module SPTR 5B4.
1
U4
SPTR5B4
A
E
IRF
TS/U1
TS/U2
TS/U3
ENA
70 71 72 73 74 75 76 77 78 65 66 68 69

9
Tobeabletooperatetherelayneedsaconstant
supply of auxiliary energy. The power supply
module forms the voltages required by the
protectionrelaymodulesandtheauxiliaryrelay
module. The module is located behind the
system front plate together with the output
relay module. The power supply module can
be withdrawn after removing the system front
plate .
The power supply module is a transformer
connected, i.e. galvanically isolated primary
and secondary side, flyback-type dc/dc
Power supply
module converter.Theprimarysideofthepowersupply moduleisprotectedwithafuse,F1,locatedon
the PC-board of the module. The fuse size is
1 A (slow).
Thepowersupplymoduleformsthesecondary
voltages required by the relay modules; i.e.
+24 V, ±12 V and +8 V. The output voltages
±12 V and +24 V are stabilized in the power
supply module, while the +5 V logic voltage
required by the relay modules is formed from
the +8 V by the stabilizers of the concerned
relay modules.
Fig. 6. Voltage levels of the power supply module.
1 A slow +8V
+12V
-12V
+24V
Uaux
80...265 V ac & dc
18...80 V dc
Unstabilized logics
voltage
Operation amplifier
voltage
Output relay coil
voltage
A green LED indicator marked Uaux on the
system front plate is illuminated when the
power supply module is in operation. The
supervision of the voltages supplying the
electronics is placed in the relay modules.
Should the secondary voltage deviate from its
rated value by more than 25 %, a self-
supervision alarm will follow. An alarm is also
received when the power supply module has
beenremovedfromtherelaycaseorwhenthe
auxiliary power supply to the relay has been
interrupted.
There are two versions of power supply
modules available. The secondary sides of
bothtypes have identical ratings, buttheinput
voltage ranges vary.
Insulation test voltage between primary and
secondary side and the protective earth
2 kV, 50 Hz, 1 min.
Rated power Pn=15 W
Input voltage ranges of the auxiliary power
modules
- type SPGU 240A1
Uaux = 80…265 V dc or ac
- type SPGU 48B2
Uaux = 18…80 V dc
B

10
Applications ThebiaseddifferentialrelaySPAD330Cused
for the winding short-circuit and interturn fault
protectionofaYNd11connectedpowertrans-
Example 1.
former, when the current transformers have
“in-side”earthings,i.e.thecurrenttransformers
have the basic connection type I.
Switch SG1
10
21
30
40
50
60
∑= 2
Setting of the matching of the power transformer
vector group:
P1
S2
P2 P1 P2
S1 S2
S1
L1
L2
L3
SPAD 330 C
..
SPAD 330 C

11
Biased differential relay SPAD 330 C used for
the winding short-circuit and interturn fault
protection of a YNd11 connected power
transformer, when the current transformers
Example 2. have”inside and outside” earthings, i.e. the
currenttransformershavethebasicconnection
type II.
Switch SG1
10
20
31
40
51
60
∑= 20
Setting of the matching of the power transformer
vector group:
SPAD 330 C
SPAD 330 C
P1
S2
P2
S1
P2 P1
S1S2
L1
L2
L3
SPAD 330 C
B

12
Example 3. Biaseddifferentialrelay SPAD330Cusedfor
the winding short-circuit and interturn fault
protection of a YNyn0 connected power
transformer, when the current transformers
have “outside” earthings, i.e. the current
transformershavethebasicconnectiontypeI.
Switch SG1
10
21
30
41
50
60
∑= 10
Setting of the matching of the power transformer
vector group:
With the adjacent setting the access of the
earth fault current flowing in the primary
circuit through the power transformer
neutral is prevented from entering the
energizing circuits of the differential relay.
SPAD 330 C
SPAD 330 C
P2
S1
P1
S2
P2 P1
S1S2
L1
L2
L3
SPAD 330 C
B

13
Example4. Biased differential relaySPAD330Cusedfor
the winding short-circuit and interturn fault
protection of a Dyn11 connected power
transformer, when the current transformers
have “inside” earthings, i.e. the current
transformershavethebasicconnectiontypeI.
Switch SG1
11
20
30
41
50
60
∑= 9
Setting of the matching of the power transformer
vector group:
SPAD 330 C
SPAD 330 C
P1
S2
P2
S1
P2P1
S2
S1
L1
L2
L3
SPAD 330 C
B

14
Biased differential relay SPAD 330 C used for
the winding short-circuit and interturn fault
protection of a Dyn11 connected power
transformer, when the current transformers
Example5. have “inside and outside” earthings, i.e . the
currenttransformershavethebasicconnection
type II.
Switch SG1
10
21
31
40
50
60
∑= 6
Setting of the matching of the power transformer
vector group:
SPAD 330 C
SPAD 330 C
P1
S2
P2
S1
P2 P1
S1S2
L1
L2
L3
SPAD 330 C

15
Technical data Energizing inputs
Rated current In1 A/5 A
Thermal current withstand
- continuously 4 A/20 A
- for 1 s 100 A/500 A
Dynamic current withstand, half-wave value 250 A/1250 A
Input impedance < 100 mΩ/< 20 mΩ
Rated frequency fn, acc. to order 50 Hz or 60 Hz
Output contact ratings
Contact interval 65-66
68-69
Rated voltage 250 V dc or ac
Continuous carry 5 A
Make and carry for 0.5 s 30 A
Make and carry for 3 s 15 A
Breaking capacity for dc, when the control
circuit time constant L/R < 40 ms, at the
control voltage levels 48/110/220 V dc 5 A/3 A/1 A
Contact material AgCdO2
Alarm contacts 70-71-72, 73-74-75,
76-77-78
Rated voltage 250 V dc or ac
Continuous carry 5 A
Make and carry for 0.5 s 10 A
Make and carry for 3 s 8 A
Breaking capacity for dc, when the control
circuit time constant L/R < 40 ms, at the
control voltage levels 48/110/220 V dc 1 A/0.25 A/0.15 A
Contact material AgCdO2
Auxiliary power module
Power supply module
- type SPGU 240A1 80…265 V dc or ac
- type SPGU 48B2 18…80 V dc
Burden of auxiliary supply under quiescent/
operating conditions ~10 W/ ~15 W
Differential relay modules SPCD 3C21, SPCD 3C22 and SPCD 3C23
Transforming ratio matching range of the HV
side current transformer 0.5…1.0 x In
Transforming ratio matching range of the LV
side current transformer 0.5...1.0 x In
Differential stage Id>
Setting range of the basic setting p 20…50 % In
Setting range of the starting ratio s 10…50 %
2nd harmonic blocking threshold 10…20 % Id
Operating time 20…50 ms
High-set instantaneous stage Id>>
Starting current setting range 20…30 x In
Operating time 10…20 ms
C

16
Spare parts
Data communication
Transmission mode Fibre-optic data bus
Data code ASCII
Selectable data transfer rates 4800 Bd or 9600 Bd
Fibre-optic interfacing module See data sheet 34 SPA 12 EN1
“Technical data and
mounting instructions for
fibre-optic cables”
Test voltages
Insulation test voltage, inputs and outputs
between themselves and to the relay frame as
per IEC 255-5 2 kV, 50 Hz, 1 min.
Impulse test voltage, inputs and outputs
between themselves and to the relay frame as
per IEC 255-5 5 kV, 1.2/50 µs, 0.5 J
High frequency interference test voltage, in-
puts and outputs between themselves and to
the relay frame as per IEC 255-5 2.5 kV, 1 MHz
Spark interference test voltage, inputs and
outputs between themselves and to the relay
frame as per SS 436 15 03 4…8 kV
Environmental conditions
Specified ambient service temperature range -10…+55°C
Temperature influence on the operating values
of the relay over the specified ambient ser-
vice temperature range < 0.2 %/°C
Long term damp heat withstand according to
IEC 68-2-3 < 95 %, +40°C, 56 d/a
Transport and storage temperature range -40...+70°C
Degree of protection by enclosure of the re-
lay case when panel mounted IP 54
Mass of the relay 6.0 kg
Differential relay module for phase L1 SPCD 3C21
Differential relay module for phase L2 SPCD 3C22
Differential relay module for phase L3 SPCD 3C23
Power supply module
Uaux = 80...265 V ac or dc SPGU 240A1
Uaux = 18...80 V dc SPGU 48B2
Output relay module SPTR 5B4
Input/output module SPTE 6B3
Fibre-optic interfacing module See alternatives in data
sheet 34 SPA 12 EN1
“Technical data and
mounting instructions
for fibre-optic cables”
B

17
Ordering numbers SPAD 330 C, differential relay RS 621 001-AA, CA, DA, FA
The last two letters of the ordering number indicate the rated frequency fn
and the auxiliary voltage range Uaux of the relay as follows:
AA equals fn=50 Hz and Uaux= 80…265 V ac/dc
CA equals fn=50 Hz and Uaux= 18…80 V dc
DA equals fn=60 Hz and Uaux= 80…265 V ac/dc
FA equals fn=60 Hz and Uaux= 18…80 V dc
Information
required
with order
Example:
1. Type designation and title of SPAD 330 C, biased differentialrelay
2. Rated frequency fn= 50 Hz
3. Ordering number RS 621 001-AA
4. Auxiliary voltage Uaux = 110 V dc
5. Accessories 2 raising frames type SPA-ZX301
2 bus interface modules SPA-ZC12 BB
2 fibre-optic cables SPA-ZF AA10
1 fibre-optic cable SPA-ZF AA5
6. Special requirements —

ABB Automation

L1
IRF
>
I
L2
I
L3
I
I
1309
[ ]
s
k>
t
0.5
0.05 1.0
13
2.5
0.5
0.04 1.0
0.5
1.5
2.5
STEP
RESET
SG1
01
1
2
3
4
5
6
7
8
20
STEP
>>
I
n
I
>
I
n
I
>>
I
>>
t
[ ]
s
>
I
>>
I
SPCJ 3C3
B
Indicators for measured values
Setting knob 1
with indicator
Stage 1
Setting knob 2
with indicator
Setting knob 3
with indicator
Stage 2
Setting knob 4
with indicator
Self-supervision alarm indicator
(Internal Relay Fault)
Display, 1 + 3 digits
Step push-button (STEP)
Programming switches SG1
Switchgroup indicator
Reset push-button (RESET)
Start/operation indicators
ABB Automation
General characteristics of
C-type relay modules
User´s manual and Technical description

2ABB Automation
General characteristics of
C-type relay modules
Contents Push-buttons .................................................................................................................. 2
Programming switches SG1............................................................................................ 2
Setting knobs.................................................................................................................. 3
Display ........................................................................................................................... 3
Display main menu ................................................................................................... 3
Display submenu....................................................................................................... 4
Setting mode ............................................................................................................. 4
Example: Operation in setting mode ......................................................................... 5
Stored information .................................................................................................... 6
Trip-test mode........................................................................................................... 7
Example: Trip-test function ...................................................................................... 8
Operation indicators....................................................................................................... 9
Fault codes...................................................................................................................... 9
Push-buttons The front panel of the relay module contains
twopush-buttons.TheSTEPbuttonisusedfor
steppingforwardin thedisplayandthe RESET
button for resetting the red indicators. Addi-
tionally, the push-buttons are used for certain
settings, e.g. for setting the address of the relay
module and the data transfer rate for the serial
communication when the modules are used in
relay packages provided with this quality. (See
section Display).
Programming
switches SG1 Part of the settings and the selections of the
operating characteristics for the relay modules
in various applications are made with the pro-
grammingswitchesSG1onthefrontpanel.The
indicator of the switchgroup glows when the
checksum of the switchgroup is shown on the
display.Thechecksumcanbeusedforchecking
thattheswitchesareproperlyset.Fig.2givesan
example of calculating the checksum.
Fig. 2. Example of calculating the checksum of programming switchgroup SG1.
Whenthechecksumcalculatedaccordingtothe
example is equal to the checksum indicated on
thedisplayoftherelaymodule,theswitchesare
properly set.
The function of the programming switches of
theindividualmeasuringrelaymodulesisspeci-
fiedinthedescriptionofthemoduleconcerned.
1MRS 750328-MUM EN
Issued 96-02-19
Version A (replaces 34 SPC 2 EN1)
Checked L-W U
Approved TK
Data subject to change without notice