Time Overcurrent Relays Type lAC
GEH-1753
INSTANTANEOUS UNIT
INTRODUCTION
The instantaneous unit is a small instantaneous
hinge-type unit which may be mounted on the right
front side of the induction unit (See Fig.
7).
Its
contacts are normally connected in parallel with
the contacts of the main unit. Its coil is connected
in
series with the operating coil of the main unit.
When the current reaches a predetermined value,
the instantaneous unit operates, closing the contact
rircuit and raising its target into view. The target
latches in the exposed position until released by
pressing the button beneath the lower left-hand
corner of the relay cover.
APPLICATION
The instantaneous unit is used on certain lAC
relay models to provide instantaneous tripping for
current exceeding a predetermined value.
OPERATING CHARACTERISTICS
The instantaneous element operates over a
4
to
1
range and has its calibration stamped on a scale
OP[IIATING
COIL
TAAGe:T
CONTACTS
MOVING
CONTACT
ASSEMBLY
Fig. 7. (8006998)
Type lAC Relay with an
Instantaneous Unit.
mounted beside the adjustable pole piece.
Time
current characteristics are shown in Fig.
10.
RATINGS
The instantaneous unit is designed to use either
of two coils having pickup ranges of
10
to
40,
and
20
to
80
amperes respectively. The current-closing
rating of the contacts is
30
amperes for voltages
not exceeding
250
volts.
BURDENS
Burden data on the instantaneous unit coils are
given in the following table:
Coil
Freq. Amp.
Volt
Imp.
Amp
Ohms
10-40
60
5
0.83
0.033
50
5
0.80
0.032
25
5
0.65
0.027
20-80
60
5
0.21
0.008
50
5
0.20
0.008
25
5
0.15
0.007
Fig. 8. (8007060)
Type IAC Relay with an
A-C Tripping Unit.
PF
0.95
0.95
0.98
0.95
0.95
0.98
7
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