Why Does Solid State Relay Burnout?

Solid State Relay (SSR) is a contactless switch composed of microelectronic circuit, discrete electronic device and power electronic power device.

During the usage of SSR, it might cause the burning if the working conditions of different relays are not concerned , or improper using of the solid state relay may also result in the sudden immediate burning in just purchasing. The following atorelays.com will introduce what causes the solid state relay burnout.

Single phase ac to ac ssr solid state relay
  1. Selection of SSR rated current. This is probably because the rated loading capability of the solid state relay you selected is lower than the practical loading power. In addition, the surge current of the load may also damage the SSR relay if it exceeds the overloading capability of SSR. For the above issue, the solid state relay should be selected properly based on the different types of loads. For the resistive load, the actual load current is not recommended to be higher than two-thirds rated current of the solid state relay. For the inductive load, the load current should be no higher than one-half rated current of SSR. It is required to equip the SSR with the overload protective device. When selecting a solid state relay, the SSR with higher rated current should be selected if possible, so as to guarantee the enough current margin.
  2. SSR DC or AC type. Please note that solid state relay is divided into DC mode and AC mode. DC SSR is only used to control DC power and DC load while AC SSR is just for controling AC power and AC load. When selecting a solid state relay, please pay attention if it is selected correctly based on the working condiitons.
  3. Installation environment. The ambient temperature also really matters. So, the heat radiator should be equipped with if the load current is higher than or equivalent to 10A. Besides,  it is also recommended to connect a varistor in series at output side as an over-current protection measure.