AnsaldoSTS F-42, Установка, эксплуатация и обслуживание

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4-4 SM 5924, Rev. 1, June 2009
circuitry) and is triggered ON and OFF as the voltage across C3 rises and falls.
A
current
limiting function is also provided to limit starting transients.
1. Inspect all soldered joints.
2. Attach a variable DC power supply to terminals 7 (+) and 4 (-). The maximum voltage
required should not exceed 35 Volts, and the current should not exceed 0.1 amp.
3. Place a 0-5 volt DC voltmeter across terminals 3 (+) and 4 (-)
4. Adjust the input voltage slowly to 32V and observe that the input current is less than 0.060
amps Current in excess of 0.060 amps may indicate a shorted component.
5. With the input voltage held at 32 volts, slowly rotate pot R15 until a point is reached which
switches the voltmeter ON and OFF. This switching point must fall within the range of R15.
6. Failure to meet this test is an indication that one or more components are faulty or the IC
(Integrated Circuit ua 723) is inoperable.
7. Perform the following steps to check out the IC.
a. The IC reference voltage, pin 4 (+) to output pin 4 (-) should fall between 6.8 and 7.5
volts. A high impedance DC voltmeter or a scope should be used for this measurement.
b. The IC input at the switch point, pin 2 (+) to pin 4 (-), should be approximately the same
value as the reference voltage. Use a high impedance voltmeter or scope for this check.
c. If Steps (a) and (b) are acceptable, and Dl is of proper value, failure to switch may
indicate a shorted output. In this case, the voltage output at pin 6 will remain at
approximately 12 volts under all conditions, and a constant voltage will appear across R1.
An open output would result in a constant OV output.
8. Current limiting - the components on the control board involved with this function are
resistors R7, R8, R9, R10, and R11, and diode D3. When attached to R5 through pins 5 and
6, the in-rush current will be limited to approximately 18amperes upon starting the inverter.
A check of component values, location, and inspection of soldered joints will insure proper
operation of this circuitry. A memory scope with probes placed across R3 is necessary to
determine the exact current limiting point.
9. If the foregoing tests for CB1 are not satisfactory, replace with an operable board.
4.5 C33-OVER VOLTAGE CONTROL BOARD (N451120-4301)
4.5.1 Checks
1. Check the following Zener diode voltages and component values. (Pre-regulated Section)
2. For Dl, use pins 4(+) and 2(-). The Zener voltage at 0.020 amperes should fall between 95V
and 105V (across D1 only).