POLARIZATION AND PHASING
13
As more and more electronics are introduced to the Heating
Trade, Polarization of incoming power and phasing of pri-
mary to secondary voltage on transformers becomes more
important.
Polarization has been apparent in the Appliance industry
since the introduction of the three prong plug, however, the
Heating Industry does not use a plug for incoming power, but
is hard wired.
Some of the electronic boards being used today, with ame
rectication, will not function properly and/or at all without
polarization of incoming power. Some also require phas-
ing between the primary and secondary sides of step-down
transformers.
These then should be wired to the furnace accordingly.
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If meter reads approximately 96 volts - the primary to secondary are in phase - if reads approximately
144 volts out of phase - reverse low voltage wires.
For ame rectication the common side of the secondary voltage (24 V) is cabinet grounded.
If you were to bench test a transformer the primary neutral and secondary common must be connect-
ed together for testing purposes.
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