Strasbaugh Machine Description
Version 1.2 - April 18, 1996 3 - 3
MACHINE DESCRIPTION
CONTROL SYSTEM OVERVIEW
This section is intended to provide a general description of the
electrical control system as an aid in understanding the operation
and maintenance of the machine. For specific details regarding
this discussion refer to the electrical schematics and component
assembly drawings in the back of this manual.
POWER DISTRIBUTION
The machine operates from a single or three phase 208 or 230 volt
60 hertz supply connected through a 30 amp circuit breaker. The
supply voltage is connected to a 75VA stepdown transformer to
provide 24 VAC to safety interlocks and a main contactor. With the
main contactor energized power is connected to the grind spindle
inverter and a 2.0 KVA stepdown transformer. The inverter drive
converts single or three phase AC power to a rectified DC voltage
bus. This bus voltage is then transformed to a pulse width
modulated three phase waveform to produce a variable voltage,
variable frequency AC waveform to drive the grind spindle
induction motor at variable speed.
The 2.0 KVA stepdown transformer provides 110 VAC to supply
the remainder of the electrical control system.
The card cage contains the programmable control components
that make up the hardware and software required to control the
machine operation. This card cage has an integral power supply to
produce the + 5 and + 15 VDC to support the card cage modules.
The 24 VDC power supply provides the DC voltage that supplies
most of the machine components including sensors, switches,
valves, and relays. The 12 VDC power supply provides the DC
voltage to operate the cathode ray tube (CRT) display on the
operator panel.
Two DC motor speed controls convert AC line voltage to a rectified
DC voltage to provide variable speed control of the permanent
magnet DC motors that drive the work spindle and rinse/spin
chuck.
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