Selection Guide

1) Determine the KVA, Amperes or wattage required by the load. Be sure to add the total number of pieces of equipment involved. The following formulas may be used to calculate the KVA, (VA)or the Amperes required, for either single or three phase installations:

Single phase	KVA	=	Volts x Amps
	(VA)		1000
	AMPS	=	KVA(VA) x 1000
			Volts
Three phase	KVA	=	1.73 x Volts x Amps
	(VA)		1000
	AMPS	=	KVA(VA) x 1000
			1.73 x Volts

1) Find out what the supply voltage ( or available voltage) is to
connect to the primary of the transformer.

2) Determine the voltage required by the load. This is the secondary
voltage or output voltage of the transformer.

4) What is the frequency of the supply source and of the
equipment? (normally 60 or 50 hertz). The frequency of the supply source and the load must be the same.

5) Does your equipment require electrical isolation from the supply or will an auto transformer with no isolation do.?

6) For control transformers if fusing is desired a terminal block model is
necessary.

7) If a control transformer is to be exported a finger-safe model option
may be required.

8) The location where the transformer will be installed will determine
whether you require no enclosure (open type). An indoor ventilated enclosure ( Nema 1. Eemac 1) or the various type of enclosures which protect the windings from moisture, particles, dust or contaminates (Nema 3R,4. or 12).

The following charts may be used to select the transformer size required.