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The IFV51AD relay is an overvoltage relay that closes its contacts when the voltage
increases to the pickup value as set on the tap block.
The IFV71AD relay is similar to the IFV51AD relay, except that it is frequenc y
compensated
to
hold
frequency.
The IFV71BD relay is similar to the IFV71AD relay except for the addition o f an
instantaneous unit, which is also
typical pickup-versus- frequency characteristic.
is determined by the setting o f a poten�iometer located in the rear o f the relay.
TIME OVE RVO LTAGE UNIT
Pickup of these relays is de fined as the voltage required to close the contacts with
the relay set at the 0. 5 time-dial position.
movable lead that connects to the tap block at the top o f the support structure (See
Figure 1) .
The tap block is marked A through N.
contains a table that shows the tap voltage for each tap setting.
The IFV relays should operate within .:!:. 10% o f the time-voltage characteristic or .:!:.
the time-dial setting times 0.010 second, whichever is greater.
show the various time-voltage characteristics for the IFV relays.
the time dial determines the length o f the time required to close the contacts for a
given voltage.
The higher the time-dial setting, the longer the operating time.
The contacts are just closed when the time dial is set to zero.
setting occurs when the time dial is set to 10 and the d isk has to travel its
maximum distance to close the contacts.
HIGH-SEISMIC TARGET AND SEA L-IN UNIT
The target and seal-in unit has two tap selections, located on the front o f the
unit.
See Figure 1.
HIGH-SEISMI C INSTANTANEOUS UNIT
The instantaneous unit setting is determined by a potentiometer located in the rear
o f the relay. See the RATINGS section for the various voltage ranges.
These relays, when not included as part o f a control panel, will be shipped in
cartons designed to protect them against damage.
relay, examine it
resulting from rough handling is evident,
transportation company and
O f fice.
Reasonable care should be exercised in unpacking the relay in order that none o f the
parts are injured or the adjustments disturbed.
I f the relays are not to be installed immediately, they should be stored in their
original cartons in a place that is free from moisture, d ust and metallic chips.
Foreign matter collected on the outside o f the case may find its way inside when the
cover is removed, and cause trouble in the operation o f the relay.
GEK-49865
CHARACTERISTICS
its calibration vJithin 7. 5%
frequency-compensated.
RECEIVING, HANDliNG AND STORAGE
for any damage sustained in transit.
promptly noti fy the nearest
frotn 50%
Pickup o f this instantaneous unit
Tap settings are made by means o f a
The nameplate on the relay
Immediately upon receipt o f a
file a damage claim at once with the
9
to
150% o f system
See Figure 10
Figures 8 and 9
The setting o f
The maximum time
I f injury or damage
General
Electric Sales
for a
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