Solid-state Relays Breakdown Prevention: High Density or Gang Mounting. What is the relationship bet

Load Current Vs. Ambient Temperature Rating Characteristic

The relationship between the load current and the ambient temperature rating is a characteristic of Solid-state Relays. It describes the amount of load current required for operating Solid-state Relays in relation to the ambient temperature measured at the specified ambient temperature measuring position during mounting and operation of the Solid-state Relays, including any self-generated heat.


1.It takes approximately 60 minutes for the heat generated from the Solid-state Relays to reach its saturation point.

2.Use actual summer temperatures as the ambient temperature.

Continued use of an Solid-state Relays at a level that exceeds the load current vs. ambient temperature rating will lead to the deterioration or breakdown of the Solid-state Relays.

Reducing Load Current When Mounting

Reducing the load current may be required for high-density or gang mounting for some Solid-state Relays.

Example: Load Current Vs. Ambient Temperature Rating for High-density or Gang-mounted G3PA-220B-VD Solid-state Relays.

For G3PA the following conditions apply when using high-density or gang mounting.

1.Up to 3 Relays can be mounted together. If mounting more than 4 Relays, they must be separated by a gap of at least 10 mm.

2.When using high-density or gang mounting, the load current must be reduced by 10%.

3.Solid-state Relays must be separated by at least 80 mm above and below each other.

Note:The above conditions will depend on the Solid-state Relays.

The solid line in the graph shows the load current vs. Solid-state Relays ambient temperature rating for vertical-mounted G3PA-220B-VD.

For high-density or gang mounting, the load current must be reduced by 10% as shown by the broken line.

When using high-density or gang mounting and the load current is 15 A, draw a horizontal line at 15 A. Where it crosses with the broken line, draw a perpendicular line downwards. (Shown as the blue arrow on the graph.) By doing this, you can see that the ambient temperature must not exceed 50°C.

Therefore, when using high-density or gang mounting, if the ambient temperature is 50°C, the load current must be kept below 15 A.

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