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OM-2065 / Operation and Maintenance Manual
90SB51 / Spec. 7015-3 / Frequency Converter
Section 3. "SOFT-START" Instructions
1. General
Following major repair such as:
• Transistor Replacement
• Wire Harness Repair or Replacement
• Transformer Replacement or Repair
• Card Cage Replacement
It is recomended that a SOFT-START procedure be followed before restarting the unit to minimize
possibilities of damage to the unit if other unrepaired problems still exist in the unit.
"SOFTSTART" is not necessary following a
simple card change in the card cage.
2. Procedure for "SOFT-START"
a. Remove DC bus fuse (F3) and two DC
filter capacitor bank fuses (F1, F2).
b. Pull out safety interlock switches to
de-activate shunt-trip on the input
circuit breaker.
c. On AMP card move NORMAL/MAIN
switch to MAIN position.
d. Apply full rated input voltage to the unit.
All lights except OUTPUT POWER
which is connected to output should
illuminate.
e. After pressing the STOP/RESET and
START (in that order) buttons, remove
ALARM II card immediately, otherwise
the unit will shutdown from undervoltage.
f. With an oscilloscope, observe base-
emitter pulses of all 24 transistors and
compare them to Figure 1 for B1-E1
and Figure 2 for B2-E2 (See also
Section 4, Figure 1).
g. Turn off input voltage. (NOTE: Allow
DC filter capacitors C7 to C16 to
discharge to 0 volts).
h. Connect a DC power supply to the DC
bus. Red bus is +, Black is - . (Power
supply capable of 12 or more volts DC).
Nov 01/90
Base Pulse for Transistor SW1
Figure 1
Base Pulse for Transistor SW2
Figure 2
Chapter 3-3
Page 1
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