G E H-1 81 4
B .
Power
General
All d evices operati ng on alternating cu rrent {AC) are affected by frequency. Si nce
n o n -s i n usoid al waveforms can be a n a lyzed as a fu n d a m e nta l fre q u e n cy p l u s
harmon ics of that fu ndamental
it follows that alternating-cu rrent d evices
{relays) wi l l be affected
applied
AC relays {and AC devices i n general)
a re significantly affected
the appl ication of non-si n usoidal waveforms.
Therefore, in order to test AC relays properly it is essential to use a test voltage a nd/o r
cu rrent waveform that is sin usoidal. The pu rity o f the sine wave {i.e., its freedom
from harmonics) can not be expressed as a fin ite n u mber for any particu lar relay;
h owever, a n y re l a y usi n g t u n ed ci rcuits, R L or RC n etwo rks, or satu rati n g
electromagnets {such as time-overcu rrent relays) wou ld be especially affected by non
si n usoidal wave forms.
Similarly, relays req u i ring DC control power should be tested usi ng DC power and not
fu l l wave rectified power. Unless the rectified su pply is wel l fi ltered, many relays w i l l
not o perate properly d ue to the d i ps i n the rectified powe r. Zener d i od es, for
example, ca n tu rn off d u ring these d i ps. As a general ru le, the DC sou rce should not
contai n more than 5% ripple.
C.
Test
The pick u p voltage should be checked on one or more taps on relays that cl ose
contacts on increasing voltage. The pickup voltage should be ta p va l ue
±
5% . The
d rop-out voltage should be checked on one or more taps on relays that close contacts
on d ecreasi ng voltage. The dropout voltage is a variable depend i n g u pon user
req u i rements. Refer to the VO LTA G E SETTING section u nd e r
S E RV I C I N G A N D
ADJUSTM ENTS.
See relay nameplates for va l u es of p i cku p o r d ropout voltages
{closi ng voltages, rig ht or left contact).
D.
Test
The time/voltage cu rves should be checked for one or more setti ngs.
Recommended test con nections for the above test a re shown in Fig u re 1 7 for the
overvoltage re lays, such as th e Types IAV5 1 A a n d IAV52A. T h e u n d e r- a n d
overvoltage relays, such as the Types IAV53A, IAV53B, IAV53C, IAV53D, IAV5 3 K,
IAV53 L , IAV53M and IAV53N, ca n be checked for time of
left contacts by usi n g
con nections shown i n Fi gure 1 7, and for closi ng
contacts
con nections shown
in Fig u re 1 8. Of cou rse the seal-i n u n it shown in
fig u re is not used i n the case of
the IAV53 B and IAV53D, but all stud n u m bers are correct for these relays.
Stud n u m bers 1 and 2 should be su bstituted for stud nu mbers 9 and 1 0 on Figu re 1 8
for testi ng the u ndervoltage contacts of the Type IAV53C relay {See i nternal d ia g ra m ,
Fig u re 5) . See i nternal connections, Figures 1 -5 for contact and coi l con nections for
IAV5 1 A, IAV52A, IAV53A, B, C
&
D and Fig u res 6 - 8, for IAV53K, IAV53 L, IAV53M a nd
IAV53N .
1 0
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