OPEN GAP
ADJUSTM ENT
FIG. 328 - OPEN GAP C H EC K
ADJUSTMENT
FIG. 32C - CLOSED GAP C H EC K
7.9
STATIC TIM E-DELAY UNDERVOLTAGE
The static time-delay undervoltage system consists of a
time-delay unit which controls an instantaneous under
voltage device. The time-delay unit is separately mounted
in the switchgear and the undervoltage device is mounted
on the breaker. Table 5 1ists the catalog n umbers available.
If the a-c control voltage is any voltage other than
208/240V ac, a control power transformer (also remotely
mounted with respect to the breaker) m ust be used. This
must have a minimum rating of 100 volt-amperes.
INSERT WIRE
GAGE
FIG. 320
-
POSITIVE TRIP CHECK
When installed, the voltage to be monitored is connected
across terminals No. 1 and No. 2 of the static delay box.
The coil of the tripping unit is connected across terminals
No. 4 and No. 5 of the static box through the secondary
disconnects of the breaker. The secondary disconnects to
be used will be shown on the breaker wiring diagram.
No more than one undervoltage tripping device should
be used in conjunction with one static time-delay unit.
The static time-delay undervoltage can also be furnished
with a thermotector control unit. Overheating of motor win
dings causes the thermotector, imbedded in the motor win
d ings, to open. This de-energizes the undervoltage device
on the breaker and drops the motor load.
7.9.1 ADJUSTMENTS
In the event the system fails, the following checks are
recommended to determine whether the undervoltage
device on the breaker of the static time delay unit is the
faulty component.
1. Check input voltages across terminals 1 and 2 on the
static box. See Table 5 for these values.
2. Check output voltages on terminals 4 and 5 with the
undervoltage device connected. See Table 5 for values.
TABLE 5 TIM E-DELAY U N ITS
CONTROL
APPROXIMATE STEADY STATE
NOMINAL DC COIL
VOLTAGE
DC OPERATING VOLTAGE
RESISTANCE
TERMINALS
TERMINALS
(OHMS)
CAT. NO.
1 & 2
4 & 5
@ 25°C
TAKYUVT-1
1 25 VDC
50
440
TAKYUVT-2
250VDC
1 00
1 600
TAKYUVT-3
208/240 VAC
1 1 0/ 1 25
1 600
25
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