Re: [CAD_CAM_EDM_DRO] Re: Bridgeport 440 volts to 220 volts.

In a message dated 11/23/2003 11:27:43 AM Mountain Standard Time,
cncgramps@... writes:
schematics out it shows heaters in the rear enclosure.
The heaters are normally found in two places in electrical equipment. The
contactor is fed by the main power disconnect. The contactor is fed from the
bottom side of that switch/disconnect.

1. Built into the main contactor, they will be the last thing before the
heavy wires going to the motor controlled by the contactor. There are either 2/3
heaters, and two smaller wires, the smaller wires are series, in the contactor
control circuit, and opening them will drop out the contactor, shorting them
will eliminate the overload/heater protection.

2. They can also be in a separate block, again with 2/3 heaters, and the same
two small wires to the control circuit.

The two smaller wires are going to an NC circuit in the overload block, that
opens when the overload is tripped.
The heaters for the higher voltage will carry a smaller current than the
heaters for the lower voltage, and often will go red hot if used on a lower
voltage/higher current situation.

The Heater block, whether integrated or separate will almost always have a
reset button on them, this can be an identify feature to look for.
bill


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