Selection of thermal relay

Update date:2017-12-29 Source:MAXGE

Selection of thermal relay

Thermal relay is mainly used for protection of motor overload, so choose must understand the situation of the motor, such as working environment, starting current, load properties, duty and allow the overload capacity, etc.

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1, in principle should be that the Ann s characteristic of thermal relay as close as possible to even overlap the overload characteristics of the motor, or under the overload characteristics of the motor, at the instant of the short-time overload of the motor and started at the same time, the thermal relay should not be affected (not action).

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2. When the heat relay is used to protect the motor of long - term working or intermittent duty, the rated current of the motor is usually selected. For example, the setting value of the thermal relay can be equal to the rated current of the motor of 0.95~1.05 times, or the median of the setting current of the heat relay is equal to the rated current of the motor, and then adjusted.

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3. When the thermal relay is used to protect the motor of repeated short-time working, the thermal relay only has a certain range of adaptability. If there is a lot of operation in a short time, the thermal relay of the current transformer with the speed saturation current should be selected.

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4, for positive and negative and special duty motor on and off frequently, should not be used as thermal relay overload protection device, and should use embedded motor winding temperature relay or thermal resistor to protect.


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www.maxge.com All Rights Reserved.

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