Heidelberg: Offset printing of offset presses

During the operation of the Heidelberg CD-102 four-color offset press, it was found that the water tank refrigeration system was out of control. The temperature set by the CP window could not be cooled (no fault display). Open the water tank electrical cabinet for inspection. Find the REL2 and REL4 solid state relay power indicator in the circuit board. Extinguished, but the 8KZM relay controlling the compressor still pulls in; after the power is turned off, the tank cooling temperature is reset, the temperature control is normal, but after the set temperature drops to the preset position, the compressor is still working, resulting in a water refrigeration cycle The device freezes and does not work properly.

It has been found through measurement that the REL2 and REL4 relays are controlled by a temperature detector next to the compressor, and the 8KZM start relay of the compressor is controlled by the REL2 and REL4 relays. It is thus determined that the REL2 and REL4 relay contacts are not returned. The main cause of loss of compressor control. So we found similar relays by referring to the solid-state relay parameters. After the relays were replaced, they were turned on and the cooling control was working properly.