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GEI-12083
All alternating current operated devices are affected by frequency.
Since' non-sinusoidal waveforms
can be analyzed as a fundamental frequency plus harmonics of the fundamental frequency, it follows that
alternating current devices (relays) will be affected by the applied waveforms.
Therefore, in order to properly test alternating current relays it is essential to use a sine wave of
current and/or voltage. The purity of the sine wave (i.e., its freedom from harmonics) cannot be expressed
as a finite number for any particular relay; however, any relay using tuned circuits, R-L or RC networks,
or saturatingelectromagnets (such as time overcurrent relays) would be especially affected by non-sinus-
oidal wave forms.
Similarly, relays requiring d-c control power should be tested using d-c and not full wave rectified
power.
Unless the rectified supply is well filtered, many relays will not operate properly due to the
dips in the rectified power.
Zener diodes, for example, can turn off during these dips. As a general
rule thed-c source should not contain more than 5 percent ripple.
ACCEPTANCE TESTS
When received, the relays should be given a visual inspection to determine if any of the relay parts
have been damaged in shipment.
Check the nameplate for the proper model of the relay and for the proper ratings as ordered on the
requi s iti on.
Check the fingers and shorting bars in the relay and case according to the internal connections
diagram.
Use figure 4 for the 12CAP15A(-)A relay and Figure 5 for the 12CAP15B(-)A relay.
All electrical checks should be performed in the relay's case in a leveled position.
If it becomes necessary to readjust or check the calibration of the relay, refer to the section
on SERVICING.
LOCATION
These relays should be installed in a location that is clean and dry, free from excessive vibration
and well lighted to facilitate inspection and testing.
MOUNTING
These relays should be mounted on a vertical surface by means of mounting studs or screws. One of
the mounting studs or screws should be permanently grounded by a conductor not less than No. 12 B&S gage
copper wire or its equivalent. The outline and panel drilling diagrams are shown in Figure 14.
CONNECTIONS
The internal connection diagrams are shown in Figures 4 and 5. The external connections diagrams
are shown in Figures 9, 11, 12 and 13.
INSTALLATION TESTS
Upon installing the relay, it is necessary to know (1) that the voltages and currents go to the
proper relay terminals, and (2) that none of the relay coils is open-circuited.
Item (1) may be checked easily by means of a phase-angle meter.
Determination of the angle between
a current and the three voltages and between a voltage and the other two currents gives all the information
necessary for a complete vector diagram. The vector diagram plus a knowledge of the direction of power
flow will immediately indicate whether or not the connections are correct.
The above test may be made with a wattmeter but the method is somewhat more involved than the phase-
angle meter test.
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