Inspection During Operation; Preparation For Internal Inspection; Internal Inspection - Hobart 6T28-600CL Operation And Maintenance Manual

OM-2244 / Operation and Maintenance Manual
DCS-600/ Series 500082 / Solid State Transformer-Rectifiers

3) Inspection During Operation

a) Make sure the meters are functioning. If a meter is suspected of being inaccurate, check it against a
test instrument.
b) Verify the lights for Input Power On and Output Contactor closed are functional. Replace if necessary.
The Overload/Over Voltage light is an LED, so it will probably not fail.
c) Verify that the fan turns on after the unit has been operating for a while. If the fan turns on
immediately on a cold unit, that might indicate a shorted fan thermostat switch.
d) Check the Starting Current potentiometer. If this control has no effect on currents above its minimum
setting, that might indicate a faulty potentiometer or faulty circuit board.

4) Preparation for Internal Inspection

a) Turn off input power at the source. Make sure that power cannot be inadvertently turned back on.
WARNING
High voltage may be present inside the GPU cabinet, even when the unit is off.
Exercise extreme caution or FATAL SHOCK may result.
WARNING
HIGH VOLTAGE - electric shock can kill! Be certain the input power source is turned
off before opening the cabinet. Stop operation immediately if a possible dangerous
fault is discovered. The front panel input contactor switch does not remove input
power from all components. Be sure capacitors are discharged before you touch.
b) Observe the front panel voltmeter and make sure the voltage is zero. If the voltage is not zero, the
capacitors still hold a charge, indicating a problem with the connection to the preload resistors.
c) Observe general condition of power-input cables and equipment output cables. Inspect for cuts and
abrasions in the insulation that could cause a short circuit. Visually inspect the output cable plug
connector for physical damage and evidence of overheating.
d) Remove the top cover.

5) Internal Inspection

a) Using compressed air or a soft brush, clean any dirt and debris from the interior.
b) Inspect terminal blocks for evidence of overheating due to loose electrical connections.
c) Inspect electrical and mechanical connections for tightness.
d) Remove the front panel screw that holds the circuit board panel. Swing the circuit board panel out to
the side.
e) Inspect the circuit board for evidence of overheating, such as burned components.
f) Inspect the hinge for the circuit board panel. If this hinge sticks or is difficult to operate, spray the
hinge with a silicone spray lubricant.
g) Inspect all wiring, leads, and cables. Inspect for cuts, abrasions, and signs of deterioration and
overheating. Inspect the leads for broken strands and terminals.
December 15, 2014 Chapter 2-3
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