Thermal Overload Protection For Hermetic Motors

The 3hm family of motor protectors can be applied to air conditioning compressors ranging from 1 to 2 hp.

Thermal overload protection for hermetic motors. As the temperature of the stator winding increases the electrical resistance of the detector increases which disturbs. Overheating or high current are generally caused by other factors that overload the motor like substituting the wrong motor or lack of proper ventilation around the. Klixon 3hm hermetic overload protector are new generation product designed to meet the demands of tomorrow s compressors. The rtd of the stator is used as one arm of the balanced wheatstone bridge.

For understanding motor thermal overload protection in induction motor we can discuss the operating principle of three phase induction motor. The amount of current through relay 49 depends on the degree of imbalance of the bridge. Another type of overload protection often called thermal overload protection is built into certain mechanical devices such as motors or engines. If larger motors 10 kw are subjected to these higher currents for a longer time damage should be expected.

Electrical mechanical and thermal motor characteristics define the frame needed for effective motor protection running stage starting stage and locked rotor conditions serve to determine the main motor parameters motor heating and thermal damage motor characteristics depend on both positive and negative sequence current in the. A thermal protector integral with the motor approved for use with the motor it protects on the basis that it will prevent dangerous overheating of the motor due to overload and failure to start a protective device integral with a motor that will protect the motor against damage due to failure to start if the motor is part of an approved. Due to such symmetrical distribution when three phase power supply. The degree of protection that an internal protection device provides is classified in the iec 60034 11 standard.

When either exceeds the motor s limit the protector will shut the motor off until it cools. There is one cylindrical stator and a three phase winding is symmetrically distributed in the inner periphery of the stator. Thermal overload relays are one of the most common and economical motor overload protection devices especially for single phase motors. The thermal overload protector on a motor monitors both motor temperature and current.

Different types of thermal protection exist and are identified by a tp code tpxxx which indicates. Tp is the abbreviation for thermal protection. They may also be used in commercial motors which must function in high pressure corrosive environments. The type of thermal overload for which the thermal protection is designed 1 digit.

In order to also ensure the thermal overload protection of the motor in the cases of supply asymmetry and loss of a phase high quality motor protection relays have mechanisms with phase failure sensitivity differential release.