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41-766.7
device. A magnetic armature, to which leaf-spring
mounted contacts are attached, is attracted to the
magnetic core upon energization of the switch. When
the switch closes, the moving contacts bridge two
stationary contacts, completing the trip circuit. Also
during this operation, two fingers on the armature
deflect a spring located on the front of the switch
which allows the operation indicator target to drop.
The target is reset from the outside of the case by a
push rod located at the bottom of the cover.
3.0 OPERATION
The block diagrams of the SSV-T and SSC-T are
shown in Figures 1, 2 and 3 (page 4 and page 5) and
the internal schematic are shown in Figures 4, 5, and
6 (page 5 and page 6). For overvoltage and overcur-
rent application, the transistor Q2 is normally not
conducting and the telephone relay is de-energized.
The transistor Q1 or current is applied to the primary
of the transformer (T) a voltage is produced on the
secondary side that tis proportional to the input. The
potentiometer (R2) is for the pick-up setting. If the
voltage from rectifier (Z1, Z2, and C2) is large
enough to exceed the breakdown voltage of zener
diode Z5, the zener diode conducts to turn on the
transistor Q2 and operate the telephone relay.
For undervoltage application, the transistors Q1 and
Q2 are normally conducting and the telephone relay
is pulled in. As soon as the input voltage drops below
the setting, the transistor Q2 is turned off and the
telephone relay is released.
4.0 CHARACTERISTICS
4.1
OVERCURRENT RELAY SSC-T
Table 1: SSC-T Burden (60 Hertz)
Range (Amps)
Lowest Setting
VA
P.F. Angle ø
.05 - 2.0
0.5
2.0 - 8.0
0.5
4.0 - 8.0
0.5
10.0 - 40.0
0.8
2
Pickup Current Setting
Highest Setting
VA
P.F. Angle ø
8.5°
4.0
12.5°
8.5°
5.0
12.5°
8.5°
5.0
12.5°
10.0°
8.0
10.5°
SSV-T and SSC-T High Drop-out Relay
Continuous
Range
0.5 - 2 amps
2.0 - 8 amps
4.0 - 16 amps
10 - 40 amps
Operating
50/60 Hz
Frequency:
Temperature
2% between 20°C
Error:
and 65°C
Dropout Ratio:
90% to 98%
Response Time:
Pickup Time = 10 - 13 ms
Dropout Time = 10 - 26 ms
For 2 to 15 times pickup setting value (Figure 10)
Transient
5%
Overreach:
Burden:
See Table 1 below
Telephone Relay
Contacts:
0.1 amps at 125 Vdc
4.2
OVER/UNDERVOLTAGE RELAY SSV-T
60- 140 Volts
Range:
140 - 320 Volts
280 - 640 Volts
Continuous Rating: Highest voltage of range setting
Operating
Frequency:
50/60 Hz
Temperature Error: 2% between -20°C and +65°C
Dropout Ratio:
92% to 99% (Figure 13)
Response Time:
Pickup Time - 7– 10 ms
Dropout Time – 14 - 40 ms
(Figure 9)
Burden:
1 VA at 120 volts 60 Hz
Telephone Relay
Contacts:
0.1 Amps at 125 Vdc
4.3
TRIP CIRCUIT
The main contacts will safely close 30 amperes at
250 volts dc and the seal in contacts of the indicating
contactor switch (when supplied) will safely carry this
current long enough to trip a circuit breaker.
One
Second
Rating
Rating
2 amps
28 amps
8 amps
112 amps
10 amps
280 amps
10 amps
280 amps
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