Pickup - GE STD15C Instructions Manual

TESTS
Before placing the relays I"
to insure that It Is correct.
CAUTION: RELAY CALIBRATION IS ACCOMPLISHED BY ADJUSTING RESISTORS R
IN ANY ONE THESE RESISTORS WILL AFFECT THE OTHER TWO SETTINGS.

PICKUP,

UNTIL FURTHER DEVIATION FROM PROPER CALIBRATION IS NOTED.
CURRENT ADJUSTMENT IS MADE ONLY AFTER THE OTHER TWO SETTINGS ARE CORRECT.
The-test circuit for pickup is shown in Fig. 14 with
current flowing in terminals 5 and 6. and the tap plugs in the 5 ampere position. and 25 percent slope
tap setting.. The pickup operation should be repeated several times until two successive readings agree
ampere and the total pickup current being interrupted between successive checks.
is found to be from 1.35
With d-c control voltage
type relay can be used as an indication of operation of the amplifier. This voltage may be applied as
in Fig. 14 and the indicating lamp will verify that the
Before adjusted for pickup. put a D.C. voltmeter (1 volt scale) on pin 2
of the sense
connections.
of 5.430 to 0.470 volts.
amplifier card to obtain the proper pickup value.
CURRENT RESTRAINT
. .
The restraint
and load boxes.
should made on the 5.0 ampere and 25% slope taps.
analysis of a single phase half wave rectified current shows the presence of
and second harmonic components as well as
This closely appmximates a typical
harmonics.
in as much as its principal components are d-c. fundamental, and second harmonic. Although the percent
second is fixed, the overall percentage may be varied by providing a path for a
of by-passed current of
component of the half wave rectified current and thus provides a means of varying the ratio of second
harmonic current to fundamental current.
The following expression shows the relationship between the percent second harmonic. the d-c component.
and the by-pass current.
Second
Figure 15 is derived fmm the above expression.
to various values of by-pass current (II) for a constant d-c set at 4.0 amperes.
The relay calibrated with a composite
will restraint with greater than twenty percent second harmonic but will operate with second
harmonic equal to twenty percent or lower.
should just begin to close its contacts
4.5-5.5 amperes.
percent tolerance at the set point to compensate for normal fluctuations in pickup. It should be noted
that the current nangitude in the rectifier branch (I ) is slightly influenced by the
pass current and should be checked to insure it
Courtesy of NationalSwitchgear.com
INSTALLATION PROCEDURE
, check the relay calibration to be used in its final location
The following test procedure is outlined for this purpose.
RESTRAINT, AND CURRENT RESTRAINT ADJUSTMENT PROCEDURES SHOULD BE REPEATED
1.65. the setting should not be disturbed.
to the proper terminals of the relay. the pickup of the telephone
The pins are counted from right to left when viewed from the card socket
card.
Apply pickup current and adjust
If the pickup is not in
adjusted by means of a Test Rectifier used in conjunction with
The test circuit is as shown in Fig. 14 with
frequency.
0.212
+ 0.5
With the d-c
This corresponds to
IN ME
BEST RESULTS CAN BE OBTAINED IF THE
open. Pickup should be 1.5 amperes with
for a voltage input to the sense amplifier card
with this setting then adjust
inrush current as seen as the relay
The by-passed current is added in phase with fundamental
100
It shows the percent second
current of two time tap value.
(I )
gradually increa
percent second harmonic (see
maintained at its proper value.
15
.
IS CHANGED.
has produced an output signal.
and pin
on the sense
to position A. Tests
percentages of
percentages of all higher even
corresponding
properly set the
at 4.0 amperes, the
by-pass current (I at a value
pickup
a two
Of by-