GEK-49865
TIME OVERVOLTAGE RELAYS
TYPES
IFV51AD
IFV71AD
IFV71BD
DESCRIPTION
The IFV51AD,
IFV71AD and
IFV71BD rel ays are singl e-phase, vol tage-operated,
induction disk relays with adjustabl e time del ay.
The I FV71BD relay contains an
instantaneous vol tage-operated unit in addition to the induction disk unit.
The induction disk unit in the I FV71AD and I FV71BD relays, and the instantaneous
unit in the IFV71BD rel ay are frequency compensated. The pickup o f these units will
remain within 7.5% o f the pickup setting at the rated system frequency over the
range o f 50% to 150% o f system frequency.
Each relay contains a target seal -in unit that operates in conjunction with the
associated disk unit. The target seal-in unit has two electrically-separate sets o f
normally-open contacts.
One set o f contacts is connected in parallel with the
contacts o f the disk unit, to protect them and their associated control spring. The
second set o f contacts is brought out o f the relay through a separate pair o f studs.
This set o f contacts may be used for monitoring or to sound an alarm, but they are
not suitabl e for use as the initiating contact in any circuit because they vdl l
operate only after the contacts o f the d isk unit have closed.
The instantaneous unit in the IFV71BD relay has two electrically-separate sets o f
normal l y-open contacts.
These contacts will close when the instantaneous unit
operates, and they may be used to initiate tripping, to sound an alarm, or to
monitor operation o f the unit.
The instantaneous unit has a self-contained target
that will show after the unit has opera ted.
Each relay is mounted in a standard C1-size drawout case, the outl ine and panel
drill ing dimensions for which are shown in Figures 15 and 16.
Internal connections
for the relays are shown in Figures 3, 4 and 5. Typical external connections are
shown in Figures 6 and 7.
APPL ICATION
The IFV51AD, IFV71AD and IFV71BD relays are single-phase, voltage-operated relays
that may be used for the protection, or time control, o f circuits where overvoltage,
or the sudden presence o f voltage, is the controlling factor.
These instructions do not purport to cover all details or
variations in
equipment
nor to provide for
every possible contingency to be met in connection with
in
s
ta
lla
t
i
o
n
,
operation
or
maintenan�•:
Should
further information be desired or should particular problems arise which are
not covered suff1c1entlg for
the purchaser's purposes, the matter should be referred
to the General
Electric Company.
To the extent required the products described here
in
meet
applicable ANSI,
IEEE and
NEMA
standards!
but no such assurance is given with respect to local codes and ordinances because they
vary greatly.
3
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