Contactor Control

Description

The PIERRE system can control contactors through a Solid State Relay (SSR) or a suitable mechanical relay.

The PIERRE Controller provides a 12 V DC control signal to the relay. The relay switches the voltage required by the contactor coil – for example, 230 V AC – while the contactor switches the connected high-power electrical load.

This configuration allows the low-voltage PIERRE control circuit to control higher-power electrical consumers that cannot be switched directly from the PIERRE Controller output.

Operating Principle

1. The PIERRE Controller activates the appropriate 12 V DC output.

2. The SSR or mechanical relay receives the control signal.

3. The relay switches the supply voltage of the contactor coil.

4. The contactor energizes and switches the connected power circuit.

5. When the control signal is removed, the relay switches off the contactor coil and the contactor returns to its normal state.

Typical Applications

Contactor control can be used for:

• electric floor heating circuits,

• HVAC equipment,

• pumps and circulation pumps,

• electric water heaters and boilers,

• sauna heaters,

• ventilation systems,

• high-power lighting circuits,

• other high-power residential, commercial, or industrial electrical loads.

Technical Advantages

• Higher-power electrical loads are not switched directly by the PIERRE Controller output.

• The control and power circuits can be appropriately separated by using a suitable relay and contactor.

• The contactor can be selected according to the power and load type of the connected equipment.

• The solution can be easily integrated into electrical distribution cabinets.

• An SSR or mechanical relay can be used, provided that its electrical characteristics are suitable for the specific control application.

Technical Notes

• In this configuration, the PIERRE Controller provides only the low-voltage control signal.

• The contactor coil is switched by a suitable SSR or mechanical relay.

• The actual high-power electrical load is switched by the main contacts of the contactor.

• The contactor's coil voltage, rated current, number of poles, and utilization category must be selected according to the controlled equipment and the electrical design.

• The switching voltage and current rating of the intermediate relay must be suitable for the contactor coil.

• Where galvanic isolation is required, a relay or SSR must be selected whose manufacturer specifications provide the required isolation.

• When switching inductive loads or contactor coils, the switching device and any required surge suppression must be selected according to the manufacturer's requirements.

• Mains-voltage and low-voltage control wiring must be appropriately separated.

• The contactor, wiring, and required overcurrent, short-circuit, and other protective devices must be sized according to the connected load.

• Installation must be carried out according to the PIERRE technical documentation, the relay and contactor manufacturer's documentation, the electrical design, and applicable electrical safety requirements.