Alstom SHPM 101, Service Manual

Page: 132 / 336

SERVICE MANUAL R5888C
QUADRAMHO Chapter 2
Page 70 of 74
6.13 Operating and reset times
Minimum (50HZ) 14ms (60Hz) 13ms
Mho characteristic
Typical (50Hz) 18–25ms (60Hz) 16–23ms
Minimum (50HZ) 19ms (60Hz) 17ms
Mho characteristic
Typical (50Hz) 25–33ms (60Hz) 22–29ms
These times include the operating times of the electro-mechanical tripping output
relays.
The maximum reset time is 36ms with the proviso that the main trip contacts
(Trip A, Trip B, Trip C, Trip 3Ph and Any Trip) are sealed in for a minimum period
of 60ms following the initial trip.
6.14 Voltage transformer (fuse failure) supervision
The voltage transformer supervision operates when zero sequence voltage is
detected without the presence of zero sequence current. This does not limit the
current sensitivity of the distance measuring elements.
Nominal V
0
detector setting 9.5V (15% V
n
).
Blocking action of distance comparators can be removed by switch SW3.
When miniature circuit breakers are used the comparators are blocked when the
MCB opens regardless of the position of SW3.
6.15 Power swing blocking
Power swing blocking zone (Zone 6) has mho or lenticular characteristic.
Aspect ratio of the lens is the same as that of Zone 3. Power swing blocking may
be enabled/disabled by SW9.
Settings: Zone 6 forward = Zone 3 f 0.3 x Zone 3 forward
Zone 6 reverse = Zone 3 r 0.3 x Zone 3 forward
Timer = 50ms
Blocking: Individual blocking of Zone 1 and/or Zone 2 and/or Zone 3 with
indication/alarm or indication/alarm only as selected by switches
on the scheme logic module. Blocking is removed if a ground fault
occurs during a power swing.
6.16 Operative ambient temperature range
The operature ambient temperature range is –25
°
to 55
°
C.
6.17 Operative frequency range
The operative freqency range is: 47 to 51Hz (f
n
= 50Hz)
56.4 to 61.2Hz (f
n
= 60Hz)