The type of relay that opens or closes its contacts due to temperature change in the environment is called thermal relay. Therefore, it is separated from standard relays. In thermal relay this situation is different.Therams are based on the heat effect created by the flowing current.
Thermal relays cannot perform their functions on their own.
Thermal Relay Working Principle
The operating logic of thermal relays is very complex.Thermics work on bimetal.Thimetals are formed by riveting two metals with expansion difference. Expansion caused by temperature difference, both bimetal is forced to deform due to the different metal. Bimetals are formed by riveting two metals with expansion differences. The bimetallic strain will be forced to change due to the difference in the temperature difference between the two metals. The thermal effect of the incoming current moves the bimetal pair and as a result activates the contacts by means of springs.
Briefly, thermal current relays cut off the load current by working with a certain delay in overload zones and the fuses can only be adjusted to a certain current value. works differently from setting. This means that the fuses only operate up to a certain current rating. The reason why it does not function against small current faults is that it cannot act very quickly. Therefore, if small faults are continuous, thermal current relays can perform their functions and protect the system. In this case, overcurrent protection is provided. On the other hand, the thermal relay also provides protection against fault currents which are continuous but small in size. To give an example; “Devices that give heat such as iron, hair dryer and water heater perform the heat control again through the thermal relay.
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