BECKWITH ELECTRIC M-0420, Инструкция

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Test Procedures – 7
7–35
Time Delay Accuracy Test
TEST SETTINGS:
Tapsetting 5 A
Pickup (% Tap Setting) 50%
Time Dial Setting (K=I
2
2
t) 25
Definite Max Time to Trip 10,000 Cycles
Function 46 Enable
1. Press ENTER. The SELECT FUNCTION LED
should turn on and the unit should display
VOLTAGE RELAY
VOLT freq curr powr C
2. Turn the knob clockwise to highlight STAT.
The unit should display
MONITOR STATUS
B setpts STAT config C
3. Press ENTER. The unit should display
MONITOR VOLTAGE STATUS
VOLT freq curr powr C
4. Turn the knob clockwise to highlight CURR.
The unit should display
MONITOR CURRENT STATUS
volt freq CURR powr C
5. Press ENTER until the unit displays
NEG SEQUENCE CURRENT
0.00 Amps
6. Turn on and set input current to: I
A
=5A –0°,
I
B
=5A –180°, I
C
=5A –0°. The display should
read “3.33 Amps, Neg.Sequence Current (I
2
')
= 2/3 I
INPUT
.”
Check at input currents of 10 A and 15 A:
I
INPUT
= 10 A, I
2
' = 2/3 (10) = 6.67 Amps
on display
I
INPUT
= 15 A, I
2
' = 2/3 (15) = 10 Amps on
display
7. Set input current to 0.00 A.
8. Press EXIT until the unit displays
BECKWITH ELECTRIC CO.
M-0420
9. Timing Accuracy Calculations
s n o it a l u c l a C y c a r u c c A g n i m i T
g n it t e s p a T A 5
p u k ci P % 0 5
) k ( l ai D e m i T 5 2
m u m i x a M e ti n if e D
p ir T o t e m i T
s el c y c 0 0 0 , 0 1
). c e s 7 6 . 6 6 1 (
I
2
' = 10 A
I
2 =
I
2
'/Tapsetting = 10/5 = 2,
where I
2
= Negative Sequence Current in
multiples of the tap setting.
K = I
2
2
t
t = k/I
2
2
= 25/(2)
2
= 25/4 = 6.25 sec.
Input Current Setting = 10(3/2) = 15 A,
for example: I
A
=15A –0°, I
B
=15A –180°,
I
C
=15A –0°.
10. Set the input current to 15.00 A and start
timing. The unit should trip after 6.25 ±3%
seconds.
11. The 46 NEGATIVE SEQUENCE OVERCUR-
RENT LED should turn on and the unit should
rotate displays
-TRGT- 06/22/93 10:19:12
Trip# = 26
-TRGT- 06/22/93 10:19:12
NEG SEQ OVERCURRENT
12. Set the input current to 0.00 A.
13. Press TARGET RESET/LAMP TEST. The
46 NEGATIVE SEQUENCE OVERCURRENT
LED should turn off. The unit should display
BECKWITH ELECTRIC CO.
M-0420
■
NOTE: The negative sequence overcurrent
function has a linear reset characteristic that takes
four minutes to reset. If you wish to retest this
function, you must wait four minutes or power
down the unit.
—END—
46 NEGATIVE SEQUENCE OVERCURRENT