Selection Parameters


Switching a single phase heater with a 1 pole relay.


Switching a three phase heater with 2 single pole relays.
Load Type: Depending on the type of load you are switching, the inrush or starting characteristic will change. The selection guide will select the correct relay for the load.

Load Voltage: Select the load voltage you are switching.

Input Signal: This is the signal you will supply to turn the relay on. Select the voltage you will apply to the input.

Load Current: This is how many amps you will be switching with the relay. If you only know the KW, you can click on the calculator image on the selection guide page to convert this to amps.

Type: Select the number of outputs on the relay. We offer 1, 2, and 3 pole relays. See the application diagrams to the left.

Heatsink: Solid state relays generate heat. To dissipate this heat, a heatsink must be used. You can buy a relay and a separate heatsink or you can buy an integrated package that has the heatsink built in.

Ambient Temperature: This is the temperature in the panel (close to the heatsink) assuming that the relay is installed. A solid state relay will generate approximately 1.2 watts per amp. For non-ventilated panels, this extra heat must be taken into account when determining the ambient temperature.

Selection Parameters

Single Phase Relay
Three Phase Relay

 
Before applying the solid state relay to the heat sink, apply a small amount of heatsink compound to the centre of the back plate of the relay. When you tighten the relay to the heatsink, the compund will spread to cover the back plate. This is very important when using three phase relays and currents greater than 25 amps. If you use a large amount of compound (you can see it oozing out the side of the relay, this can cause the relay to over-heat and fail.