OTC Welbee M350 II, Owner'S Manual

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Maintenance and Inspection
Chapter 8
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If insulation resistance measurement and withstand voltage test is necessary, please contact your dealer.
• When measuring insulation resistance and testing withstand voltage, follow the steps below.
Refer to the schematic diagram, parts layout, and parts list for maintenance.
– Disconnect the input power cable and grounding cable from the disconnect switch and short-circuit
the input terminal.
– Short-circuit the positive (+) and the negative ( - ) sides of the output terminal.
– Unground all the case grounding cables (line No.80, total of 6 positions) and insulate them with
insulation tape.
– For DR1, 2, and 4, short-circuit the AC side and positive (+) output side, and short-circuit the AC side
and negative (-) output side.
– Short-circuit between TR1 (C1) and (E1C2), TR1 (E1C2) and (E2), TR3 (C2) and (E2), TR5(C) and (E),
TR6(C) and (E).
– Apply NF.
– After finishing insulation resistance measurement, return the above to the original state.
‡ The customer MUST NOT perform the withstand voltage test. If withstand voltage test
is necessary, ensure to contact your dealer.
‡ Insulation resistance measurement should be conducted by qualified persons or
persons familiar with the welding machine. Also, fence and other necessary measures
should be taken around the welding machine to prevent other people from getting in
the nearby area.
CAUTION
‡ Conducting insulation resistance measurement by customer may result in injury or
equipment failure. For insulation resistance measurement, be sure to ask your dealer.
CAUTION
‡
After finishing insulation resistance measurement, it is necessary to remove the
shortcircuit cables and return the welding power source to the original state.
If the power is turned on without returning it to the original state, the welding power
source will burn out.