Control with system controller (without CM-RC)

When operating the capacity control without a BITZER compressor module, the following must be observed.

System controller

The capacity regulators allow for a high cycling rate, and the regulator outputs must be dimensioned accordingly. Not all electromagnetic relays are designed for years of switching at the frequency required for fine-step control. The following regulator outputs for inductive loads with high switching frequency (CRII solenoid coils) are offered by regulator manufacturers:

• SSR (solid state relais): contactless semiconductor relay
• TRIAC
• Connect an external module downstream of the controller output if necessary.

An EMC interference suppressor should be connected in parallel with each solenoid coil, if necessary, in order to ensure the required service life at high cycling rates – see also:

• AT-300: Schematic wiring diagrams for BITZER products

If the control logic is taken over by the system controller, it is essential to observe the following time intervals:

• Intermittent CR valve: min. 5 s open, min. 5 s closed
• All CR valves closed / all cylinder banks de-energised (0% capacity): max. 2 min. Depending on operating conditions, the time span may be even more limited. After 2 min, either a cylinder bank should be reactivated, or the compressor should be switched off completely.

For maximum cycling rate and minimum running times, see the respective operating instructions for the compressor.

For switching times during motor start (star-delta start, part winding start), refer to the respective operating instructions and

• AT-330: Starting modes for BITZER compressors