VersaPulse Select - Power Switching, Conditioning, Distribution; Input Power; Circuit Breaker On, Keyswitch off; Turn on

THEORY OF OPERATION
4-5
Versapulse Select Service Manual
0621-499-01 01/94
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4.2 POWER SWITCHING, CONDITIONING, DISTRIBUTION
4.2.1 Input Power
Refer to 8 - 2. The Versapulse Select operates off of 200- 240 VAC line voltage. The main circuit breaker is
rated at 30 amps. The mains and ground inputs are wired into TB1. From TB1, the two mains run to the
circuit breaker, and then through a line filter (US systems may not include the line filter). From the line filter
the mains lines parallel out to two different areas.
Through F1/F2 and TB1 to the primary side of isolation transformer T1. TB1 allows tapping of
isolation transformer T1 to match the incoming line voltage. The transformer has two secondary
windings. One is the unswitched 24 VAC turn-on supply. The other is a switched 220 VAC supply
to the fan, pump and DC supplies.
Through the main contactor to the high voltage power supply.
4.2.2 Circuit Breaker on, Keyswitch off
Refer to 8-2. When the circuit breaker is turned on, the AC mains voltage is applied to contacts 1 and 3 of the
main contactor and across the primary of isolation transformer T1. Transformer T1 has two secondaries; a
switched secondary and an unswitched secondary.
The unswitched secondary is the 24 VAC supply for the turn-on circuitry. The switched secondary is the 220
VAC supply to the fan, pump, DC power supply, and display power supply. Note that even with the
keyswitch off, there are dangerous voltages present inside the unit.
With the keyswitch in the OFF position, the SW1-A OFF contact of the key switch is closed and the SW1-A
START contact is open. The main contactor is de-energized and its contacts (L1, L2, L3) are open. K1 and K2
are de-energized.
4.2.3 Turn on
Refer to 8-2. To turn the unit on, the keyswitch is turned to the START position, then released to the ON
position.
When the key switch is turned to the START position, it closes its SW1-A START contacts and opens its SW1-
A OFF contacts. 24 VAC is available from the unswitched secondary of the transformer to the control wind-
ings of K1 and the main contactor. Both energize.
When the main contactor energizes, its four sets of contacts close. Contacts L1 and L2 close to apply primary
power to the high voltage power supply (HVPS). Contact L3 closes to apply the switched secondary current
to the fan, pump, display power supply and low voltage power supply. SW4 closes to complete a portion of
the "hold on" current loop to the control winding of the main contactor.
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