GE MVAX 11 User manual

GE
Grid Solutions
MVAX
11, 12, 21, 31, 91
Technical Manual
Trip Circuit Supervision Relay
Publication reference: R8010RB

SAFETY SECTION

STANDARD SAFETY STATEMENTS AND EXTERNAL LABEL INFORMATION FOR
General Electric EQUIPMENT
1. INTRODUCTION
This Safety Section and the relevant equipment documentation provide full
information on safe handling, commissioning and testing of this equipment.
This Safety Section also includes reference to typical equipment label
markings.
The technical data in this Safety Section is typical only, see the technical
data section of the relevant equipment documentation for data specific to
a particular equipment.
Before carrying out any work on the equipment the user
should be familiar with the contents of this Safety Section
and the ratings on the equipment’s rating label.
Reference should be made to the external connection diagram before the
equipment is installed, commissioned or serviced.
Language specific, self-adhesive User Interface labels are provided in a bag
for some equipment.
2. HEALTH AND SAFETY
The information in the Safety Section of the equipment documentation is
intended to ensure that equipment is properly installed and handled in order
to maintain it in a safe condition.
It is assumed that everyone who will be associated with the equipment will
be familiar with the contents of this Safety Section, or the Safety Guide
(SFTY/4L M).
When electrical equipment is in operation, dangerous voltages will be
present in certain parts of the equipment. Failure to observe warning
notices, incorrect use, or improper use may endanger personnel and
equipment and also cause personal injury or physical damage.
Before working in the terminal strip area, the equipment must be isolated.
Proper and safe operation of the equipment depends on appropriate
shipping and handling, proper storage, installation and commissioning, and
on careful operation, maintenance and servicing. For this reason only
qualified personnel may work on or operate the equipment.
Qualified personnel are individuals who:
Are familiar with the installation, commissioning, and operation of the
equipment and of the system to which it is being connected;
Are able to safely perform switching operations in accordance with
accepted safety engineering practices and are authorized to energize
and de-energize equipment and to isolate, ground, and label it;
Are trained in the care and use of safety apparatus in accordance with
safety engineering practices;
Are trained in emergency procedures (first aid).

The equipment documentation gives instructions for its installation,
commissioning, and operation. However, the manuals cannot cover all
conceivable circumstances or include detailed information on all topics. In
the event of questions or specific problems, do not take any action
without proper authorization. Contact the appropriate General Electric
technical sales office and request the necessary information.

3. SYMBOLS AND LABELS ON THE EQUIPMENT
For safety reasons the following symbols which may be used on the
equipment or referred to in the equipment documentation, should be
understood before it is installed or commissioned.
3.1 Symbols
Caution: refer to equipment documentation Caution: risk of electric shock
Protective Conductor (*Earth) terminal
Functional/Protective Conductor (*Earth)
terminal
Note: This symbol may also be used for a Protective Conductor (Earth) terminal if
that terminal is part of a terminal block or sub-assembly e.g. power supply.
*NOTE: THE TERM EARTH USED THROUGHOUT THIS TECHNICAL
MANUAL IS THE DIRECT EQUIVALENT OF THE NORTH
AMERICAN TERM GROUND.
3.2 Labels
See Safety Guide (SFTY/4L M) for typical equipment labeling information.

4. INSTALLING, COMMISSIONING AND SERVICING
Equipment connections
Personnel undertaking installation, commissioning or servicing work
for this equipment should be aware of the correct working
procedures to ensure safety.
The equipment documentation should be consulted before
installing, commissioning, or servicing the equipment.
Terminals exposed during installation, commissioning and
maintenance may present a hazardous voltage unless the
equipment is electrically isolated.
Any disassembly of the equipment may expose parts at hazardous
voltage, also electronic parts may be damaged if suitable
electrostatic voltage discharge (ESD) precautions are not taken.
If there is unlocked access to the rear of the equipment, care should
be taken by all personnel to avoid electric shock or energy hazards.
Voltage and current connections should be made using insulated
crimp terminations to ensure that terminal block insulation
requirements are maintained for safety.
Watchdog (self-monitoring) contacts are provided in
numerical relays to indicate the health of the device. General
Electric strongly recommends that these contacts are hardwired
into the substation's automation system, for alarm purposes.
To ensure that wires are correctly terminated the correct crimp
terminal and tool for the wire size should be used.
The equipment must be connected in accordance with
the appropriate connection diagram.
Protection Class I Equipment
Before energizing the equipment it must be earthed using
the protective conductor terminal, if provided, or the
appropriate termination of the supply plug in the case of
plug connected equipment.
The protective conductor (earth) connection must not be
removed since the protection against electric shock
provided by the equipment would be lost.
When the protective (earth) conductor terminal (PCT) is also
used to terminate cable screens, etc., it is essential that the
integrity of the protective (earth) conductor is checked after
the addition or removal of such functional earth
connections. For M4 stud PCTs the integrity of the protective
(earth) connections should be ensured by use of a locknut or
similar.
The recommended minimum protective conductor (earth) wire size
is 2.5 mm² (3.3 mm² for North America) unless otherwise stated in
the technical data section of the equipment documentation, or

otherwise required by local or country wiring regulations.
The protective conductor (earth) connection must be low-
inductance and as short as possible.
All connections to the equipment must have a defined potential.
Connections that are pre-wired, but not used, should preferably be
grounded when binary inputs and output relays are isolated. When
binary inputs and output relays are connected to common
potential, the pre-wired but unused connections should be
connected to the common potential of the grouped connections.
Before energizing the equipment, the following should be checked:
Voltage rating/polarity (rating label/equipment
documentation);
CT circuit rating (rating label) and integrity of connections;
Protective fuse rating;
Integrity of the protective conductor (earth) connection
(where applicable);
Voltage and current rating of external wiring, applicable to
the application.
Accidental touching of exposed terminals
If working in an area of restricted space, such as a cubicle, where
there is a risk of electric shock due to accidental touching of
terminals which do not comply with IP20 rating, then a suitable
protective barrier should be provided.
Equipment use
If the equipment is used in a manner not specified by the
manufacturer, the protection provided by the equipment may be
impaired.
Removal of the equipment front panel/cover
Removal of the equipment front panel/cover may expose
hazardous live parts, which must not be touched until the electrical
power is removed.
UL and CSA listed or recognized equipment
To maintain UL and CSA approvals the equipment should be
installed using UL and/or CSA listed or recognized parts of the
following type: connection cables, protective fuses/fuseholders or
circuit breakers, insulation crimp terminals, and replacement internal
battery, as specified in the equipment documentation.

Equipment operating conditions
The equipment should be operated within the specified electrical
and environmental limits.
Current transformer circuits
Do not open the secondary circuit of a live CT since the high
voltage produced may be lethal to personnel and could damage
insulation. Generally, for safety, the secondary of the line CT must
be shorted before opening any connections to it.
For most equipment with ring-terminal connections, the threaded
terminal block for current transformer termination has automatic CT
shorting on removal of the module. Therefore external shorting of
the CTs may not be required, the equipment documentation should
be checked to see if this applies.
For equipment with pin-terminal connections, the threaded terminal
block for current transformer termination does NOT have automatic
CT shorting on removal of the module.
External resistors, including voltage dependent resistors (VDRs)
Where external resistors, including voltage dependent resistors
(VDRs), are fitted to the equipment, these may present a risk of
electric shock or burns, if touched.
Battery replacement
Where internal batteries are fitted they should be replaced with the
recommended type and be installed with the correct polarity to
avoid possible damage to the equipment, buildings and persons.
Insulation and dielectric strength testing
Insulation testing may leave capacitors charged up to a hazardous
voltage. At the end of each part of the test, the voltage should be
gradually reduced to zero, to discharge capacitors, before the test
leads are disconnected.
Insertion of modules and pcb cards
Modules and PCB cards must not be inserted into or withdrawn from
the equipment whilst it is energized, since this may result in damage.
Insertion and withdrawal of extender cards
Extender cards are available for some equipment. If an extender
card is used, this should not be inserted or withdrawn from the
equipment whilst it is energized. This is to avoid possible shock or
damage hazards. Hazardous live voltages may be accessible on
the extender card.
External test blocks and test plugs
Great care should be taken when using external test blocks and test
plugs such as the MMLG, MMLB and MiCOM P990 types, hazardous
voltages may be accessible when using these. *CT shorting links
must be in place before the insertion or removal of MMLB test plugs,
to avoid potentially lethal voltages.
*Note:
When a MiCOM P992 Test Plu
g
is inserted into the MiCOM

Service Manual R8010RB
MVAX Page 1/24
TYPE MVAX
TRIP CIRCUIT
SUPERVISION RELAY

Service Manual R8010RB
MVAX Page 3/24
CONTENTS
1. INSTALLATION 5
1.1 General 5
1.2 Unpacking 5
1.3 Storage 5
1.4 Relay mounting 5
2. COMMISSIONING 6
2.1 General 6
2.2 Wiring 6
2.3 Insulation 6
2.4 MVAX 11 6
2.5 MVAX 12 6
2.6 MVAX 21, 31, 91 7
2.7 Electrical operation tests 7
2.7.1 MVAX 11 only 7
2.7.2 MVAX 12 only 7
2.7.3 MVAX 21 only 8
2.7.4 MVAX 31 (MVAX 91 – 3 separate MVAX 31’s in a size 8 case) 9
2.7.5 MVAX 31 04 only 10
2.7.6 MVAX 31 with CCT breaker closure inhibit contact 11
3. MAINTENANCE 13
4. MECHANICAL SETTINGS 13
4.1 General 13
4.1.1 With the armature closed the clearance between the back of the armature and the
back stop should be 0.075/0.2mm (0.003"/0.008"). 13
4.1.2 Nominal armature gap open. 13
4.2 Contact settings 14
4.2.1 MVAX 11 (Unit RL1.) 14
4.2.2 MVAX 12, MVAX 21, 31 (Unit RL1.) 14
4.2.3 MVAX 21 (Unit RL2), MVAX 31 (Units RL2and RL3)14
4.3 Mechanical flag settings 14

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4.3.1 Hand reset reverse flags 14
4.3.2 Self reset reverse flags 14
5. PROBLEM ANALYSIS 15
5.1 Failure to operate/reset 15
5.2 Output contacts not changing state. 15
5.3 Reset time on MVAX 12 too short. 15
6. SPARES 15
6.1 Repairs 15
7. COMMISSIONING TEST RECORD 23
FIGURES
Figure 1: Circuit and application diagram – trip supervision relay 16
Figure 2: Supervision of interposing control relay type MVAW 17
Figure 3: Supervision of tripping relay type MVAJ 17
Figure 4: Circuit diagram – MVAX21 trip circuit supervision relay without preclosing
supervision 18
Figure 5: Application diagram – MVAX21 trip circuit supervision relay without preclosing
supervision 19
Figure 6: Circuit diagram – MVAX31 trip circuit supervision relay with preclosing
supervision 20
Figure 7: Application diagram - MVAX31 trip circuit supervision relay with preclosing
supervision 21

Service Manual R8010RB
MVAX Page 5/24
1. INSTALLATION
1.1
1.2
1.3
1.4
General
Protective relays, although generally of robust construction, require careful treatment prior to
installation on site. By observing a few simple rules the possiblity of premature failure is
eliminated and a high degree of performance can be expected.
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 has been sustained in transit, a claim should be made to the transport
company concerned immediately, and the nearest General Electric representative
should be promptly notified.
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.
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.
Relay mounting
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 centers.
For individually mounted relays these dimensions will also be found in Publications R6103
MVAX 11 and R6010 MVAX 12, 21, 31 and 91.
Publication R7012 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.
Publication R6001 is a leaflet on the modular integrated drawout system of protective relays.
Publication R6014 is a list of recommended suppliers for the pre-insulated connectors.

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2. COMMISSIONING
2.1 General
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.
Carefully remove the rubber band securing the flag mechanism.
Check 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.
2.2 Wiring
Check that ratings of the relay agree with the supplies to which it is to be connected.
Check all wiring connections to the relay, including the case earthing connection above the
terminal block. It is especially important that dc supplies are wired with the correct polarity.
The relay diagram number appears inside the case.
2.3 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, subsequently must be replaced.
2.4 MVAX 11
With MVAX 11 relays check that all wiring complies to the appropriate application diagram to
ensure that the relay is wired correctly.
2.5 MVAX 12
With MVAX 12 relays, check that terminal 13 of the relay case is wired to the POSITIVE of
the trip supply.

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MVAX Page 7/24
2.6 MVAX 21, 31, 91
For MVAX 21, 31 and 91 relays, check the external wiring to ensure the correct values of
external resistors (where appropriate) are wired to the correct relay terminals, in accordance
with the following table and the appropriate application diagram.
Supply volts Alarm supply circuit
REXT1Trip supply circuit REXT2 and REXT3, as appropriate
24/27 -270 ohm
30/34 –470 ohm
48/54 240 ohm 1,500 ohm
110/125 1,500 ohm 4,000 ohm
*1,200 ohm
220/250 4,100 ohm 2 off 4,000 ohm in series
* S/R reverse flag
2.7 Electrical operation tests
2.7.1 MVAX 11 only
Isolate the MVAX from the trip supply batteries by removing fuses/links as necessary.
Connect a supply across relay terminals 21 – 27 and supply the relevant voltage from the list
below. Check that the current is within those figures stated in the same column. Repeat
again only using terminals 27 – 28.
Rated voltage range (V) 30/34 48/54 110/125 120/250
Test voltage (V) 30 48 110 220
Terminals 21 – 27 46.1/56.3mA 24.1/29.5mA 11/13.4mA 11.4/14mA
Terminals 27 – 28 46.1/56.3mA 24.1/29.5mA 11/13.4mA 11.4/14mA
2.7.2 MVAX 12 only
Isolate the relay from the trip supply batteries by removing fuses/links as necessary.
Using an ohmmeter check the resistance across the relay side of the fuses/links. Provided
there are no parallel paths, the resistance should be within ±10% of the following:
MVAX 12 rating range (V) 24/27 30/34 48/54 110/125 220/250
Relay resistance (Ohms):
No flag/hand reset flag 2
contacts
4
contacts
710 416 1170
620 2970 1760 10370 7470 33100 23100
Relay resistance (Ohms):
No flag/hand reverse flag 2
contacts
4
contacts
590 407 940
590 2330 1740 8670 6770 27100 22100
Connect a variable dc supply to the isolated circuit ensuring correct polarity is observed
(Terminal 13 of the relay must be maintained POSITIVE).

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Apply 75% of the relay’s lower voltage of the voltage rating range. Check that the relay
operates satisfactorily and that the flag indication can be reset. Reduce the voltage slowly
until the relay drops-off. Check that this occurs between 25% to 40% of the lower voltage
rating, as indicated below:
V rating range 24/27 30/34 48/54 110/125 220/250
75% of lower (V) 18 22.5 36 82.5 165
25-40% of lower (V) 6 – 9.6 7.5 – 12 12 – 19.2 27.5 – 44 55 – 88
Replace all links and fuses. Check that the relay operates and manually reset the flag. With
alarm circuits operational, temporarily remove a trip supply fuse. Check that the appropriate
alarms are initiated. Replace the fuse and reset the relay flag.
2.7.3 MVAX 21 only
The following tests assume trip and alarm supply battery voltages are equal to the maximum
voltage of the relay’s voltage rating range. For other voltages within the relays normal
voltage rating range, tolerance bands for other measured supply voltages should be altered
pro-rata.
A table (Table 1) of acceptable tolerances for each test is given below.
Measure the trip supply and alarm supply voltages immediately prior to the tests
and note.
Test 1
With the circuit breaker open, check that no voltage appears across terminals 13 and 14 of
the relay. Check that the voltage appearing across terminals 21(+) and 28 comply with that
given in Table 1 (alarm supply) and that the front relay, RL1, has operated. Reset its flag.
Test 2
With the circuit breaker closed, check that the front relay remains operated. Measure the
voltage across terminals 13(+) and 14. Ensure that it complies with Table 1
(Trip supply).
Test 3
With the circuit breaker closed, apply a temporary short circuit across the external resistor
REXT2* of the trip supply circuit. Ensure the CB does not trip. Remove the short circuit and
re-apply it across terminals 13 and 14 of the relay. Check that RL1 drops-off to initiate
alarm circuits and that RL1 flag indication is given. Ensure the CB does not trip. Remove
the short circuit and reset the flag/alarms.
*Note: Where 2 resistors are used in series for REXT2, a temporary short
circuit should be applied across each resistor in turn.
Test 4
With the circuit breaker closed, operate, or simulate operation of the associated trip relay.
Note that the CB trips but ensure that RL1 of the MVAX does not operate.
RL1 and RL2 units are slugged on drop-off to prevent mal-operation during the transition
period.

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MVAX Page 9/24
Relay V. rating 24/27 30/34 48/54 110/125 220/250
Ref. V. for tolerance 27 34 48 110 220
Hand reset
flag Full volts (no ext. R) Full volts (no ext. R) 35.3 – 38.8 29.1 – 36.3 24.9 – 32.5
Test 1
(Alarm
supply) Self reset
flag Full volts (no ext. R) Full volts (no ext. R) 37.1 – 40.4 38.2 – 46.6 28.5 – 37.0
Hand reset
flag 15.0 – 17.0 18.0 – 20.5 25.8 – 29.8 53.6 – 61.2 107.0 – 120.9
Test 2
(Trip
supply) Self reset
flag 12.0 – 14.0 18.0 – 20.5 25.8 – 29.8 53.6 – 61.2 107.0 – 120.9
Table 1
2.7.4 MVAX 31 (MVAX 91 – 3 separate MVAX 31’s in a size 8 case)
The following tests assume trip and alarm battery voltages are equal to the maximum
voltage of the relay’s voltage rating range. For other voltages within the relay’s normal
voltage rating range, tolerance bands for other measured supply voltages should be altered
pro-rata. A table (Table 2) of acceptable tolerances for each test is given below.
Measure the trip supply and alarm supply voltages immediately prior to the tests and note.
Tests 1 and 2
With the circuit breaker open, check the voltage across terminals 13(+) and 14(–ve) of the
relay. This should comply with the voltage tolerance limited given in Table 2. Repeat for
terminals 21(+) and 22(–ve) of the relay. The same voltage limits apply. Both these voltages
are derived from the trip supply.
Check the voltage across terminals 27(+) and 28(–ve) of the relay. This should be within the
limits given in Table 2 for the alarm supply. Note that the front relay unit RL1 is picked-up
and reset its flag.
Test 3
With the circuit breaker closed check that the front relay RL1, remains operated. Check that
no voltage appears across terminals 21 and 22 of the relay. Ensure the voltage across
terminals 13(+) and 14(–ve) has increased from that obtained in Test 1 to that indicated in
Table 2.
Test 4
With the circuit breaker closed, as in test 3 above, check that the voltage between terminals
14(+) and 22(–ve) is zero. Measure the resistance between terminals 14 and 22 which
should comply within ±10% of the values given in Table 2. (Note: This test check that
contact 52–b is open in the breaker closed condition).
Test 5
With the circuit breaker closed, as above, apply a temporary short circuit across REXT2* of
the trip supply circuit. Ensure the CB does not trip. Remove the short circuit and re-apply it
across terminals 13 and 14 of the relay. Check that RL1 drops off to initiate alarm circuits
and that RL1 flag indication is given. Remove the short circuit and reset the flag/alarms.
*Note: Where 2 resistors are used in series for REXT2, a temporary short
circuit should be applied across each resistor in turn.

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Page 10/24 MVAX
Test 6
With the circuit breaker closed, operate, or simulate operation of the associated trip relay.
Ensure the CB trips but ensure that RL1 of the MVAX does not operate.
The MVAX relay units are slugged on drop-off to prevent mal-operation during the transition
period.
Relay V. rating 24/27 30/34 48/54 110/125 220/250
Ref. V. for tolerance 27 34 54 125 250
Hand
reset flag 7.8 – 8.2V 9.4 – 9.8V 13.6 – 14.2V 27.9 – 29.4V 55.3 – 58.4V
Test 1
(Trip
supply) Self reset
flag 6.3 – 6.7V 9.4 – 9.8V 13.6 – 14.2V 27.9 – 29.4V 55.3 – 58.4V
Hand
reset flag Full volts (no ext. R) Full volts (no ext. R) 36.5 – 42.7V 31.3 – 38.8V 27.3 – 33.8V
Test 2
(Alarm
supply) Self reset
flag Full volts (no ext. R) Full volts (no ext. R) 38.2 – 39.3V 40.9 – 43.7V 31.1 – 34.0V
Hand
reset flag 15.7 – 16.3V 18.8–19.7V 27.1 – 28.5V 55.8 – 58.9V 110.6 –116.8V
Test 3
(Trip
supply) Self reset
flag 12.7 – 13.3V 18.8–19.7V 27.1 – 28.5V 55.8 – 58.9V 110.6 –116.8V
Hand
reset flag 665 1085 3100 7400 14700
Test 4
Self reset
flag 522 1085 3100 7400 14700
Table 2
2.7.5 MVAX 31 04 only
The following test assume trip and alarm supply battery voltages are equal to the maximum
voltage for the relays voltage rating range. For other voltages within the relays normal
voltage rating range, tolerance bands for other measured supply voltages should be altered
pro-rata. A Table (Table 1) of acceptable tolerance for the test is given.
Measure the trip supply and alarm supply voltages immediately prior to tests
and note.
Test 1
With the circuit breakers open, check that no voltage appears across terminals 13 and 14, 21
and 22 of the relay. Check that the voltage appearing across terminals 27(+) and 28 comply
with that given in Figure 1 (alarm supply) and that the front relay RL1, has operated. Reset
the flag.
Test 2
With the circuit breakers closed, check that the front relay remains operated. Measure the
voltage across terminals 13(+), 14, 21(+) and 22. Ensure that these comply with Figure 1
(trip supply).
Test 3
With the circuit breakers closed, apply a temporary short circuit across each of the external
resistors REXT2(1)* and REXT2(2)* of the trip supply circuits. Ensure the circuit breakers do
not trip. Remove the short circuits and reapply them across terminals 13 and 14 and 22 of
the relay. Check that RL1 drops-off to initiate alarm circuits and that the RL1 flag indication
is given. Ensure the circuit breakers do not trip. Remove the short circuits and reset the
flag/alarms.
*Note: Where 2 resistors are used in series for REXT2, a temporary short
circuit should be applied across each resistor in turn.