Service Manual

Type MCAA 11, 12, 13, 14, 15

Current Operated Auxiliary Relays
R8047B

HANDLING OF ELECTRONIC EQUIPMENT

A person's normal movements can easily generate electrostatic potentials of several thousand volts.
Discharge of these voltages into semiconductor devices when handling electronic circuits can cause
serious damage, which often may not be immediately apparent but the reliability of the circuit will have
been reduced.
The electronic circuits of GEC ALSTHOM T&D Protection & Control Limited products are completely safe
from electrostatic discharge when housed in the case. Do not expose them to the risk of damage by
withdrawing modules unnecessarily.
Each module incorporates the highest practicable protection for its semiconductor devices. However, if it
becomes necessary to withdraw a module, the following precautions should be taken to preserve the high
reliability and long life for which the equipment has been designed and manufactured.
1. Before removing a module, ensure that you are at the same electrostatic potential as the equipment
by touching the case.
2. Handle the module by its front-plate, frame, or edges of the printed circuit board.
Avoid touching the electronic components, printed circuit track or connectors.
3. Do not pass the module to any person without first ensuring that you are both at the same
electrostatic potential. Shaking hands achieves equipotential.
4. Place the module on an antistatic surface, or on a conducting surface which is at the same
potential as yourself.
5. Store or transport the module in a conductive bag.
More information on safe working procedures for all electronic equipment can be found in BS5783 and
IEC 147-0F.
If you are making measurements on the internal electronic circuitry of an equipment in service, it is
preferable that you are earthed to the case with a conductive wrist strap.
Wrist straps should have a resistance to ground between 500k – 10M ohms. If a wrist strap is not
available, you should maintain regular contact with the case to prevent the build up of static.
Instrumentation which may be used for making measurements should be earthed to the case whenever
possible.
GEC ALSTHOM T&D Protection & Control Limited strongly recommends that detailed investigations on the
electronic circuitry, or modification work, should be carried out in a Special Handling Area such as
described in BS5783 or IEC 147-0F.
Page 2
 CONTENTS

1. INSTALLATION 5
1.1 General 5
1.2 Unpacking 5
1.3 Storage 5
1.4 Site 5
2. COMMISSIONING 6
2.1 Ratings 6
2.2 Wiring 6
2.3 Preliminaries 6
2.3.1 Armature and flags 6
2.4 Insulation 7
3. MAINTENANCE 7
4. MECHANICAL SETTINGS 7
4.1 General 7
4.2 Contact Settings 8
4.2.1 Relays with armature operated contacts 8
4.2.2 Relays with mechanically operated contacts 8
4.2.3 Relays with mechanically latched contacts, types MCAA 13, 14 and 15 9
4.3 Mechanical settings related to the latch for MCAA 13, 14 and 15 10
4.4 Electrical reset mechanism for MCAA 14 and 15 10
4.5 Mechanical flag settings 10
4.5.1 Settings for self reset units for MCAA 11 10
4.5.2 Settings for hand and self reset units for MCAA 12 10
4.5.3 Settings for hand reset and electrically reset units for MCAA 13, 14 and 15 11
4.6 Settings for reset levers on hand reset and hand/electrically reset units for
MCAA 13, 15 11
5. PROBLEM ANALYSIS 11
5.1 Failure to operate/reset 11
5.2 Output contacts not changing state 11
6. SPARES 12
7. COMMISSIONING TEST RECORD 13
REPAIR FORM 15

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Page 4
Section 1. INSTALLATION

1.1 General
Protective relays, although generally of robust construction, require careful
treatment prior to installation and a wise selection of site. By observing a few simple
rules the possibility of premature failure is eliminated and a high degree of
performance can be expected.
The relays are either despatched individually or as part of a panel/rack mounted
assembly in cartons specifically designed to protect them from damage.
Relays should be examined immediately they are received to ensure that no
damage has been sustained in transit. If damage due to rough handling is evident,
a claim should be made to the transport company concerned immediately, and
GEC ALSTHOM T&D Protection & Control Limited promptly notified. Relays
which are supplied unmounted and not intended for immediate installation should be
returned to their protective polythene bags.
1.2 Unpacking
Care must be taken when unpacking and installing the relays so that none of the
parts are damaged or their settings altered, and must at all times be handled by
skilled persons only.
Relays should be examined for any wedges, clamps, or rubber bands necessary to
secure moving parts to prevent damage during transit and these should be removed
after installation and before commissioning.
Relays which have been removed from their cases should not be left in situations
where they are exposed to dust or damp. This particularly applies to installations
which are being carried out at the same time as constructional work.
1.3 Storage
If relays are not installed immediately upon receipt they should be stored in a place
free from dust and moisture in their original cartons and where de-humidifier bags
have been included in the packing they should be retained. The action of the de-
humidifier crystals will be impaired if the bag has been exposed to ambient
conditions and may be restored by gently heating the bag for about an hour, prior to
replacing it in the carton.
Dust which collects on a carton may, on subsequent unpacking, find its way into the
relay; in damp conditions the carton and packing may become impregnated with
moisture and the de-humidifying agent will lose its efficiency.
The storage temperature range is –25°C to +70°C.
1.4 Site
The installation should be clean, dry and reasonably free from dust and excessive
vibration. The site should preferably be well illuminated to facilitate inspection.
An outline diagram is normally supplied showing panel cut-outs and hole centres.
For individually mounted relays these dimensions will also be found in Publication
R–6047.
Publication R–7012 is a Parts Catalogue and Assembly Instructions. This document
will be useful when individual relays are to be assembled as a composite rack or
panel mounted assembly.

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 Publication R–6001 is a leaflet on the modular integrated drawout system.
Publication R–6014 is a list of recommended suppliers for the pre-insulated
connectors.

Section 2. COMMISSIONING

2.1 Ratings
Check that ratings of relay agree with the supplies to which it is to be connected.
2.2 Wiring
Check all wiring connections to the relay, including the case earthing connection
above the terminal block. It is especially important that dc supplies and magnetic
blowout contacts are wired with the correct polarity. The relay diagram number
appears inside the case.
2.3 Preliminaries
Before leaving the factory all relays are accurately adjusted, tested and carefully
packed. Hence there should be no need for any re-adjustment on commissioning.
Moving parts are held in position during transit by rubber bands and packing. These
should be removed carefully.
To gain access to the relay first loosen the captive cover screws. Then carefully
remove the cover from the case.
The module can then be removed from the case by grasping the handles at the top
and bottom of the front plate and pulling forwards.
Care must be taken to ensure that mechanical settings of the element are not
disturbed.
2.3.1 Armature and flags
Carefully remove the rubber band securing the flag mechanism.
Check that the bottom end of the contact operating card has not been dislodged from
the slot in the armature extension and that the ends of the push rods are located in
the holes in the contact springs.
Carefully actuate the armature of each unit in turn with a small screwdriver/probe.
Note immediately after the point where any make contacts just close there is a
further small movement of the armature. This ensures that contact follow through
and wiping action is present. Repeat similarly with break contacts on armature
release.
On units fitted with hand reset flag indicators, check that the flag is free to fall
before, or just as, any make contacts close.
Replace the module in the case and refit the cover. Make sure that the reset
mechanism in the cover is correctly located with respect to the relay element, and
that the flag (or mechanism) can be reset.

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2.4 Insulation
The relay, and its associated wiring, may be insulation tested between:
a) all electrically isolated circuits
b) all circuits and earth
An electronic or brushless insulation tester should be used, having a dc voltage not
exceeding 1000V. Accessible terminals of the same circuit should first be strapped
together. Deliberate circuit earthing links, removed for the tests, must subsequently
be replaced.
Check operation or electrical reset by energising the relay with a current equal to Is
(minimum setting current). The appropriate terminals should be identified from the
internal wiring diagram normally supplied.
Disconnect external wiring from these terminals to allow application of the test
supply.
The relays should switch cleanly with one movement.
Is is marked on either the lower hand strip or front plate.
MCAA14 and 15 relays may have voltage operated reset mechanisms. Energise the
appropriate terminals with 80% of the lower rated voltage. The relay should reset
cleanly in one movement.
To check shorting contact across coil remove module, whilst Is is flowing. The
current should be uninterrupted.
Restore any external wiring connections that may have been disturbed during the
above tests.

Section 3. MAINTENANCE

Periodic maintenance is not necessary. However, periodic inspection and test is

recommended. this should be carried out every 12 months or more often if the relay
is operated frequently or is mounted in poor environmental conditions.
Repeat checks in Section 2.3 with emphasis on contact wear and condition.
Mechanical settings may be checked against the table in Section 4.
Tests in Section 2.4 should be carried out to prove operation.

Section 4. MECHANICAL SETTINGS

4.1 General
Armature gap measurements should be made with the top of the feeler gauge level
with the centre line of the core.
Contact pressures are measured with a gramme gauge at the contact tips.
In general, contact gaps and follow through are defined by quoting an armature gap
at which the tips should be just closed or just open. Some mechanically operated
contact gap must be measured directly with feeler gauges at the contact tips.
The relay contact state is always defined with the relay in the unenergised position,
unless otherwise specified on the appropriate circuit diagram.

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 Contact type Symbol used on diagrams
Normal duty Heavy duty
Make M Z
(Normally open)
Break B Y
(Normally closed)
Break before make BBM –
(Changeover)
With the armature closed the clearance between the back of the armature and the
back stop should be 0.003"/0.008".
Nominal armature gap open 0.050"/0.060" for all types.
4.2 Contact Settings
4.2.1 Relays with armature operated contacts.
Types MCAA11 self reset, MCAA12 self reset contacts only, for hand reset
contacts, refer to Section 4.2.2.
Contact settings for:
Normal/heavy duty make and break contacts.
With the armature closed onto a 0.011" feeler gauge the make contacts should be
closed, but should be open using a 0.013" feeler gauge.
With the armature closed onto a 0.027" feeler gauge the break contact should be
open, but should be closed using a 0.029" feeler gauge.
Force to just close the make contacts 20/25 grams.
Force to just open the break contacts 18/23 grams.
Contact settings for:
Normal duty break before make contacts.
With the armature closed onto a 0.011" feeler gauge the make contacts should be
closed, but should be open using a 0.013" feeler gauge.
With the armature closed onto a 0.028" feeler gauge the break contact should be
open, but should be closed using a 0.031" feeler gauge.
Force to just close the make contacts 20/25 grams.
The force is measured at the outer tip.
The force to just open the break contacts – 18/23 grams.
The force is measured at the inner tip.
4.2.2 Relays with mechanically operated contacts
Types MCAA 12 hand reset contacts only, for self reset contacts refer to
Section 4.2.1.
Contact settings for:
Normal duty make and break long hand reset contacts.

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 The following settings are with the mechanism operated (flag down).
Contact gap: (make) 0.07"/0.1"
(break) 0.07"/0.08"
Force to just close the make contact 25/35 gm.
Force to just open the break contact 35/40 gm.
The gap between the top of the armature and the make moving contact should be
0.130" minimum when the flag is down.
Relays with four pairs of hand reset contact.
It will be necessary to remove the force of the upper contacts from the lower set.
This is carried out by carefully lifting the push rod upwards and then measuring the
appropriate contact force.
Also with the flag down the force to just move the armature off the backstop should
be 60/80 grams. This force is measured at the end of the armature and is adjusted by
the screw which is located between the contact blades near to the contact blocks.
Contact setting for:
Normal duty make and break short hand reset contacts.
The following settings are with the mechanism operated (flag down).
Contact gaps: 0.070"/0.080"
Force to just close the make contacts 18/23 gm.
Force to just open the break contacts 20/25 gm.
4.2.3 Relays with mechanically latched contacts, types MCAA 13, 14 and 15.
Contact settings for:
Normal/heavy duty make and break contacts with the armature closed onto a 0.018"
feeler gauge, the make contacts should be closed, but should be open with a 0.022"
feeler gauge.
When the armature has settled back on the catch the break contact gap should be
0.060"/0.070".
Force to just close the make contacts 20/25 gm.
Force to just open the break contacts 18/23 gm.
Contact settings for:
Normal duty break before make contacts.
With the armature closed onto a 0.018" feeler gauge the make contact should be
closed, but should be open with a 0.022" feeler gauge.
With the armature closed onto a 0.021" feeler gauge the break contact should be
open, but should be closed using a 0.025" feeler gauge.
Force to just close the make contact – 20/25 gm.
The force is measured at the outer tip.
Force to just open the break contact 18/23 gm.
The force is measured at the inner tip.

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 Contact setting for:
Cut off contact – lower left hand contact.
First set the lower lug on the armature extension so that the top of the roller is level
with the top of the plastic catch when the relay is in the operated position.
Remove the operating wire from the plastic block on the moving contact.
Set the contact gap to 0.045"/0.055".
Force to just close the make contact 12/15 grams.
Reposition the operating wire which should locate freely in the hole in the plastic
block on the moving contact blade. If necessary bend the wire to suit.
4.3 Mechanical settings related to the latch for MCAA 13, 14 and 15
The upper limiting lug should be clear of the cross roller and armature backstop in
all positions.
Care should be taken to ensure that the upper lug still prevents the cross roller from
riding up and over the armature extension.
With the armature closed the force to lift the cross roller above the latch should be
40/50 grams.
With the armature closed onto a 0.003" feeler gauge the cross roller should pass
clear of the plastic catch, but with a 0.006" feeler gauge the roller should not clear
the catch. To achieve this the armature extension should be bent. The upper face of
the plastic catch should remain tangential to a circle centred on the armature hinge.
The armature should return freely to the fully open position when partly closed and
released and the reset arm should fall freely to the fully operated position when
partly reset and released.
4.4 Electrical reset mechanism for MCAA 14 and 15
With the unit de-energised the lever arm should rest on the frame with the control
spring just touching.
When the reset armature is closed onto a 0.005" feeler gauge it should reset the main
element, but not reset with a 0.01" feeler gauge.
If the reset mechanism has been moved or changed, it may be necessary to adjust the
position of the reset electromagnet by means of the mounting screws which are
located in slotted holes.
4.5 Mechanical flag settings
4.5.1 Settings for self reset units for MCAA 11
With the armature closed onto a 0.013" feeler gauge the flag should be free to fall,
but should not fall using a 0.018" feeler gauge. Adjustment is made to the catch
spring on the flag.
4.5.2 Settings for hand and self reset units for MCAA 12
With the armature closed onto a 0.005" feeler gauge the flag should be free to fall,
but should remain unoperated with a 0.01" feeler gauge. Adjustment should be made
equally to both flag catch springs on the flag.
With the armature held closed the force to raise the flag, such that the roller just
touches the long contacts is between 60 – 80 grams. This force is measured at the
reset tab on the flag and adjustment by means of the spring on flag side arms.

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4.5.3 Settings for hand reset and electrically reset units for MCAA 13, 14 and 15
With the armature closed onto a 0.023" feeler gauge the flag shall be free to fall, but
should remain unoperated with a 0.028" feeler gauge. Adjustment is made to the flag
catch spring on the flag.
4.6 Settings for reset levers on hand reset and hand/electrically reset units for
MCAA 13, 15
The distance between the reset lever and the top of the reset arm should be 0.25".
This is measured above the roller pivot and is adjusted by bending the reset lever.

Section 5. PROBLEM ANALYSIS

5.1 Failure to operate/reset

Check diagram for correct input connections.
Check minimum setting current Is this is marked on the front of the module.
Ensure the power supply is capable of supplying the necessary power.
With MCAA13, 14 and 15, check that the relays are not latched in the operated/reset
position.
The reset coils may be voltage operated, check front plate for details and diagram for
connections.
Some relays may be fitted with cut-off contacts – refer to diagram.
Flag spring may be jammed between armature and core face, preventing armature
closure.
Check internal wiring.
Check continuity – result open circuit.
Coil open circuit.
Cut-off contact in series with coil open circuit.
Internal wiring damaged.
Diode bridge damaged – voltage operated reset only.
Series resistor open circuit.
Check continuity – result short circuit.
Diode bridge damaged – relay takes excessive current – voltage operated reset
only.
5.2 Output contacts not changing state
Operating card/push rod not in position.
Check output terminals with reference to diagram.
Internal wiring diagram.
Contamination of contacts.
Contacts should be cleaned with the burnishing tool. Supplied in relay tool kits.
On no account should knives, files or abrasive materials be used.
Check mechanical settings as per Section 4.

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Section 6. SPARES

When ordering spares, quote the full relay model number and any component
reference numbers, or briefly describe the parts required.
Should the need arise for the equipment to be returned to GEC ALSTHOM T&D
Protection & Control Limited for repair, then the form at the back of this manual
should be completed and sent with the equipment together with a copy of any
commissioning test results.

Page 12
Section 7. COMMISSIONING TEST RECORD

AUXILIARY RELAY TYPE MCAA DATE _________________

STATION __________________________ CIRCUIT_____________________________

MODEL NO. _______________________ SERIAL NO. __________________________

WIRING DIA. NO. __________________

CURRENT SETTING _______ A, ________ Hz DC (delete)

ELECTRICAL RESET (if fitted) ___ / ___ V Is _______ A ____ Hz DC (delete)

1. Outgoing contact availability

Number and type of contact
Device ref. Make (open) * Break (closed) * Change-over

* Note: Contact state with the unit(s) de-energised.

2. RELAY VISUALLY INSPECTED:

a) From freedom from damage in transit (tick)
b) That contact follow-through and pressures
appear satisfactory. (tick)

3. CONTACT WIRING CHECK

Outgoing contact wiring checked to wiring diagram (tick)

4. ELECTRICAL OPERATION
Satisfactory operation obtained at the current setting level Is (tick)
ELECTRICAL RESET UNIT (If fitted)
The relay satisfactorily resets at:
a) 80% ___ V of the lower voltage of the nominal voltage
rating range ____ Hz DC (delete)
or b) at the nominal reset current Is ______ A, ______ Hz DC (delete)
(tick)

6. OPERATION (FLAG) INDICATORS YES NO (delete)

Satisfactory operation obtained (tick)

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7. HAND RESET MECHANISMS YES (delete if not applicable)
The following functions satisfactorily with the cover in position:–

Flag reset Contact reset Flag contact reset (combined)

8. REMARKS

___________________________________ ____________________________________
Commissioning Engineer Customer Witness

___________________________________ ____________________________________
Date Date

Page 14

Page 15
 REPAIR FORM

Please complete this form and return it to GEC ALSTHOM T&D Protection & Control
Limited with the equipment to be repaired. This form may also be used in the case of
application queries.

GEC ALSTHOM T&D Protection & Control Limited

St. Leonards Works
Stafford
ST17 4LX,
England
For: After Sales Service Department

Customer Ref: __________________ Model No: _________________

GECA Contract Ref: __________________ Serial No: _________________
Date: __________________

1. What parameters were in use at the time the fault occurred?

AC volts _____________ Main VT/Test set

DC volts _____________ Battery/Power supply
AC current _____________ Main CT/Test set
Frequency _____________

2. Which type of test was being used? ________________________________________

3. Were all the external components fitted where required? Yes/No

(Delete as appropriate.)

4. List the relay settings being used

______________________________________________________________________
______________________________________________________________________
______________________________________________________________________

5. What did you expect to happen?

______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________

continued overleaf

Page 15
✁
6. What did happen?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________

7. When did the fault occur?

Instant Yes/No Intermittent Yes/No

Time delayed Yes/No (Delete as appropriate).

By how long? __________

8. What indications if any did the relay show?

______________________________________________________________________
______________________________________________________________________
______________________________________________________________________

9. Was there any visual damage?

______________________________________________________________________
______________________________________________________________________
______________________________________________________________________

10. Any other remarks which may be useful:

______________________________________________________________________
______________________________________________________________________
______________________________________________________________________

___________________________________ ____________________________________
Signature Title

___________________________________ ____________________________________
Name (in capitals) Company name

Page 16
✁
 GEC ALSTHOM T&D PROTECTION & CONTROL LIMITED
St Leonards Works, Stafford ST17 4LX, England
Tel: 44 (0) 1785 223251 Telex: 36240 Fax: 44 (0) 1785 212232

GEC ALSTHOM T&D PROTECTION & CONTROLE

Avenue de Figuières - 34975 Lattes Cedex - France
Tél: (33) 67 20 54 54 Télèx: 485 093 F Fax: (33) 67 20 54 99

Our policy is one of continuous product development and the right is reserved to supply equipment which may vary from that described.
©1996 GEC ALSTHOM T&D Protection & Control Limited.

Publication R8047B 039610 CPS Printed in England.