Control Features - Emerson ZX User Manual

2.3 Control Features

As mentioned earlier, the ZX CDU Control System evolves around the E2 Board and one of it's
primary functions is the Automatic Liquid Injection system that ensures that the ZX Compressor
operates within a safe envelope. This is carried out with an injection of Liquid Refrigerant Into the
Scroll Suction, this process has a global patent on it. The Injection is based on measuring the
Scroll Head Temperatures and sending that data to the E2 Board which has a built-in Algorithm
that converts this temperature signal specific digital instructions and sends to a Stepper Motor
Driving An EXV. The EXV accordingly supplies Liquid Refrigerant to keep the Compressor Head
Temperatures within Safe Levels.
Other Compressor Protection features are Compressor Phase Reversal (Scroll Compressor
Will Not Compress In Reverse ), Voltage Imbalance Protection , Loss of Phase Protection,
Motor Current Overload (Built-In and therefore External Current Protection not Required ),
Non-Adjustable High And Low Pressure Switches (Automatic Reset For Nos. Of Trips, Then
Lockout [For HP Only] And Require Manual Restart), Liquid Floodback Protection
(Measurement of Discharge Superheat To Predict Liquid Floodback), Fresh Start Programs (To
Ensure Safe Start-Ups After Long Periods Of Inactivity) and the Crankcase Heater (Energized
When Compressor Stops)
Due to the Condenser Fan Speed Control Function, the Ambient Operating Range can be
reduced to –30 C which is useful in start-up and for operations during winter operation. The
ambient temperature below which Fan Speed Control Option is recommended is 25 C .
The Base Control function is for Connection Of Optional / Customer
Supplied Functions such as Temperature Controller or Thermostat, Electric Defrost Heater
Contactor, Evaporator Fan Contactor, Output For Dialer, Compatibility With CPC's Einstein
Control & Monitoring System (coming)
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