GEK-49865
CHARACTERISTICS
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 frequency
compensated to hold its calibration vJithin 7. 5% frotn 50% to 150% o f system
frequency.
The IFV71BD relay is similar to the IFV71AD relay except for the addition o f an
instantaneous unit, which is also frequency-compensated.
See Figure 10 for a
typical pickup-versus- frequency characteristic.
Pickup o f this instantaneous unit
is determined by the setting o f a poten�iometer located in the rear o f the relay.
TIME OVE RVOLTAGE UNIT
Pickup of these relays is defined as the voltage required to close the contacts with
the relay set at the 0. 5 time-dial position.
Tap settings are made by means o f a
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.
The nameplate on the relay
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.
Figures 8 and 9
show the various time-voltage characteristics for the IFV relays.
The setting o f
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. The maximum time
setting occurs when the time dial is set to 10 and the disk 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-SEISMIC 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.
RECEIVING, HANDliNG AND STORAGE
These relays, when not included as part o f a control panel, will be shipped in
cartons designed to protect them against damage.
Immediately upon receipt o f a
relay, examine it for any damage sustained in transit.
I f injury or damage
resulting from rough handling is evident, file a damage claim at once with the
transportation company and promptly notify the nearest General Electric Sales
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, dust 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.
9
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