TECHNICAL REFERENCE
461
June 1999
96-8000
12.12 POWER S UPPLY A SSEMBLY
All power to the control passes through the power supply assembly. It is located on the upper right corner of
the control cabinet.
MAIN C IRCUIT B REAKER CB1
Circuit breaker CB1 (see chart for ratings) is primarily used to protect the spindle drive and to shut off all power
to the control. The locking On/Off handle on the outside of the control cabinet will shut this breaker off when it
is unlocked. A trip of this breaker indicates a SERIOUS overload problem and should not be reset without
investigating the cause of the trip. The full circuit breaker ratings are listed in the following chart.
MAIN C ONTACTOR K1
Main contactor K1 is used to turn the control on and off. The POWER ON switch applies power to the coil of
K1 and after it is energized, auxiliary contacts on K1 continues to apply power to the coil. The POWER OFF
switch on the front panel will always remove power from this contactor.
When the main contactor is off, the only power used by the control is supplied through two ½ amp fuses to the
circuit that activates the contactor. An overvoltage or lightning strike will blow these fuses and shut off the main
contactor.
The power to operate the main contactor is supplied from a 24V AC control transformer that is primary fused at
½ amp. This ensures that the only circuit powered when the machine is turned off is this transformer and only
low voltage is present at the front panel on/off switches.
LOW V OLTAGE P OWER S UPPLY
The low voltage power supply provides +5V DC, +12V DC, and -12V DC to all of the logic sections of the
control. It operates from 115V AC nominal input power. It will continue to operate correctly over a 90V AC to
133V AC range.
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