Basics

When operating loads with currents above 20A or with different voltages (e.g. 5V or 230V), the use of relays or contactors is required. These components enable the safe control of such loads without overloading the motorhome's control components.

Relays

Properties of relays

A relay is an electrically controlled switch. It consists of a control circuit (coil) and a working circuit (load). The working circuit is closed or opened by applying a voltage to the coil.

- Suitable applications:

- Control of devices up to 20A.

- Adaptation for deviating voltages (e.g. 5V devices in a 12V system).

Circuit diagram (simplified illustration)

1st control circuit: The coil of the relay is connected to the control current source.

2nd working circuit: The current for the load flows via the relay's switching contacts.

Connection of relays

Safety instructions

- The working circuit must be fused externally to prevent damage to the load or the wiring.

- The relay must be firmly integrated into the wiring, as removing it can impair the protection of the circuit.

Example: Lightbar

When connecting a lightbar via a relay:

- The current from the lightbar is routed via the relay's operating circuit.

- Note: The power consumption of the lightbar is not displayed in an app-based control system, as the switch only controls the coil of the relay.

Contactors

Properties of contactors

Contactors are powerful relays designed for loads with high current requirements and devices with mains voltage (230V).

- Area of application: Appliances such as air conditioning systems or electric heaters in motorhomes.

Special features

- When switching, contactors produce a clearly audible ‘click-clack’ sound that signals mechanical switching.

- Important note: Working with 230V can be life-threatening. It should only be carried out by qualified persons.

Summary

- Relays and contactors enable the safe control of large loads or devices with deviating voltages.

- The working circuit must always be fused.

- Special care must be taken when using contactors with 230V.