21.12.98 Operating manual
04_GB ACP 3000 — 0.37–15.0
21
Berges electronic • D–51709 Marienheide-Rodt • Tel. 02264/17-0 • Fax 02264/17126
Assume:
The voltage from L1 to L2 = L
a
The voltage from L2 to L3 = L
b
The voltage from L3 to L1 = L
c
The average line voltage = L
avg
Determine the absolute value of the difference between each of the line voltages (L
a
, L
b
and L
c
) and L
avg
. (Subtract the two values and disregard the sign of the result.) Consider
the results of this calculation to be L
aa
, L
ba
, and L
ca
.
Example: Measured phase voltages of 395, 400, and 405 would result in a calculated
phase imbalance of 1.25%.
If the resulting phase imbalance exceeds 2%, consult your local power company or plant
maintenance personnel and ask them to investigate this problem and recommend methods
of correcting this condition.
Phase imbalance can also cause damage to motors running direct on line. A 2% imbalance
requires a 5% derating factor on the motor, 3% imbalance requires a 10% derating. 4% re-
quires an 18% derating.
NEVER USE POWER-FACTOR IMPROVEMENT CAPACITORS ON THE ACP MOTOR
TERMINALS, M1, M2, AND M3, OR DAMAGE TO THE INVERTER'S SEMICONDUC-
TORS WILL RESULT!
3.6.2 Line Protection
It is necessary to provide either a circuit breaker or a fused disconnect switch on the input
AC line in accordance with all applicable electrical codes. The following rules should be
used to select the correct size of the input line fuses or circuit breaker.
A. Sizing
The ACP inverter is able to withstand a 150% overload for 60 seconds. Minimum voltage
rating for the protection device should be 250 VAC for models 3300-3 to 3302-2, and 600
VAC for models 3600-7 to 3615-0.
B. Fuse Type
To guarantee a maximum protection of the inverter fuses should be used for current Limi-
tation. These fuses should have a breaking capacity of 200,000 A
eff
. The following tables
shows the recommended values in amps for all ACP-inverters.
For 230/400 V mains supplies we recommend time-lag type NEOZED-fuses.
L
avg
L
a
L
b
L
c
++
3
-------------------------------
395 400 405++
3
------------------------------------------ 400== =
Phase Imbalance
L
aa
L
ba
L
ca
++
2 L
avg
()
----------------------------------------
100%×
505++
2 400×
----------------------
100%× 1.25%===
ATTENTION!
ATTENTION!
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