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Thermal and current protectors


Thermal protection is necessary because electrical and electronic equipment inevitably generates heat that can cause damage.

Current protection interrupts the electrical circuit when the electrical current exceeds a predetermined level. Overcurrent can be caused by overload or short circuit. Current protections with push button are used to turn off electrical equipment, machinery and systems when there is overcurrent and prevent them from restarting suddenly, except after manually switching the power supply.

Sibel Ltd. is a distributor of the major European manufacturer of thermal protection - the German company Thermik.

Here you will find the following products related to thermal protection and current protection:

  • Thermal protection with bimetallic thermo-switch

Thermal protections with bimetallic thermo-switch are mainly applied to small and medium electric motors, transformers and electric machines. Thermik also produces bimetallic thermal protectors with a built-in thermistor. It can be connected in parallel or in series to the bimetallic contact. When the connection is in parallel, the contact does not reset automatically when the motor cools down. To close the contact again, a manual power switch on is required. This prevents accidents in the event of a sudden resumption of movement after the machine has cooled down. If there is a series connection of a thermistor, the current sensitivity of the thermal protection increases and thus reacts faster in case of overheating.

  • Thermistors

Thermistors, are thermal protectors that contain a semiconductor thermosensitive resistor (thermistor). Their use is in medium-sized electric motors. As the temperature changes, the resistance of the thermistor changes. In PTC thermistors, as the temperature rises, the resistance increases.

With NTC thermistors, the opposite is true - it decreases.

The PTC and NTC thermistors are set to a certain temperature, around which the resistance of the thermistor changes dramatically. This sends a pulse to the control equipment connected to the motor and it responds to the signal according to its algorithm.

  • Unipolar manually resettable current protections with push button
Button current protectors are microswitches that work on a bimetallic principle. They are designed to prevent overload and short circuit when certain current values are reached. They are used in various systems, control panels, power supplies, motor protections and many others.
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