GE MVAX 11, Technical Manual

R8010

R

B

Service Manual

Page 8/24 

MVAX 

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 
R

EXT

2* 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 R

EXT

2, 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.