The current mode of protection type is commonly used in electrical control circuit and method

Are the major factors influence the rise of temperature of the electric control circuit, current size, cooling condition, electricity time 1, short circuit protection, Several times to dozens times rated current) Damage: high temperature insulation damage, powerful electric stress make mechanical damage. Protection features: reliable, instantaneous power off. Note: the short circuit protection should not be influenced by the starting current and action. Short circuit protection device: fuse, automatic switch instructions: 1) , automatic switch, the measuring element and actuators together, to cut off the power supply directly. 2) Fuse melts itself is measured and actuators, and cut off the power supply directly. 2, over current protection, No more than 2. Five times rating) Protections: instantaneous power off. Overload protection device: over-current relay: over-current relay overcurrent protection through the contactor ( Actuators) Complete, in order to cut the overcurrent, contactor contact capacity needs to increase. 3, overload protection, Usually 1. Within the rating of 5 times) Protections: inverse time characteristics. Overload protection, thermal relay: thermal relay action not immediately after reset. Thermistor as measuring element thermal relay, or heating element embedded in the motor winding, to more accurately measure the temperature rise. When the temperature of the unit under test to specify, to cut off the circuit protection. 4, less current protection ( Generally in dc) Protections: instantaneous power off. Owe current protection device: owe current relay, open phase protection (5 Delta connection) Protections: inverse time characteristics. Phase failure protection device: open phase protection of thermal relay