12
OM 200MICRO
Signal Converter Board
The AC current signal generated by the starter is converted by the signal converter board into a 0-5
VDC signal that is directly proportional to the chiller amp draw. The amp draw signal is sent to the
ADI board for conditioning and then to the M280 controller.
Figure 8, Signal Converter Board
TB1
TB2
Guardistor Board
The Guardistor board monitors the motor winding temperature through the embedded Guardistor
sensors. If the motor temperature rises to an unsafe level, the board will signal the M280 controller
and the chiller will be shut down.
Figure 9, Guardistor Board
Power Transformers
Transformers T2, T3 and T4 provide operating power to the MicroTech controller and it’s associated
components. T2 is a conventional ferrite core transformer that converts 120VAC from the control
transformer into 24VAC. T3 and T4 are transformers that convert 24VAC from T2 into a center-tapped
18VAC.
