, tested separately.
To locate a ground in the regulator or other part, disconnect the lines
running to the welder from the switch. The test lamps used in the previous
tests are connected, one end of lamp cord to the switch, the other end to a
binding post of the regulator. Connect the other side of the switch to some
part of the regulator housing. (This must be a clean connection to a bolt
head or the paint should be scraped off.) Close the switch. If the lamps
light, the regulator winding or some part of the switch is "grounded" to
the iron base or core of the regulator. If the lamps do not light, this
part of the apparatus is clear.
This test can be easily applied to any part of the welder outfit by
connecting to the current carrying part of the apparatus, and to the iron
base or frame that should not carry current. If the lamps light, it
indicates that the insulation is broken down or is defective.
An A.C. voltmeter can, of course, be substituted for the lamps, or a D.C.
voltmeter with D.C. current can be used in making the tests.
A short circuit in the primary is caused by the insulation of the coils
becoming defective and allowing the bare copper wires to touch each other.
This may result in a "burn out" of one or more of the transformer coils, if
the trouble is in the transformer, or in the continued blowing of fuses in
the line. Feel of each coil separately. If a short circuit exists in a coil
it will heat excessively.
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