电动机配用断路器的选择

低压断路器又称自动开关或自动空气开关，一般分为塑料外壳式(又称装置式)和框架式(又称万能式)两大类。在水泥厂，380V 245kW及以下的电动机多选用塑壳式断路器。
　　断路器按用途可分为保护配电线路用、保护电动机用、保护照明线路用和漏电保护用等。常用的有DZ5、DZ15、DZ20、DW15、DW17型等系列产品。
1、电动机保护用断路器选用原则
　　1)长延时电流整定值等于电动机额定电流。
　　2)瞬时整定电流：对于保护笼型电动机的断路器，瞬时整定电流等于(8～15)倍电动机额定电流，取决于被保护笼型电动机的型号、容量和起动条件。对于保护绕线转子电动机的断路器，瞬时整定电流等于(3～6)倍电动机额定电流，取决于被保护绕线转子电动机的型号、容量及起动条件。
　　3)6倍长延时电流整定值的可返回时间大于或等于电动机的起动时间。按起动时负载的轻重，可选用返回时间1s、3s、5s、8s、15s中的某一档。
2、断路器规格型号的对表速查
　　根据电动机的容量或额定电流，即可查出其配用断路器的规格型号。例如一台Y160M－4、11kW电动机，从速查表查得应配用DZ5－50型、热脱扣器额定电流为25A的断路器。
3、断路器脱扣器整定电流的速算口诀
“电动机瞬动，千瓦20倍”
　　“热脱扣器，按额定值”
　　上述口诀是指控制保护一台380V三相笼型电动机的断路器，其电磁脱扣瞬时动作整定电流，可按“kW数的20倍”选用。对于热脱扣器，则按电动机的额定电流选择。

Select motor equipped with circuit breakers
Low-voltage circuit breakers , also known as automatic switches or automatic air switch , generally divided into the plastic housing type ( also known as device type ) and the frame ( also known as Universal ) two categories. In the cement plant , 380V 245kW electric motor and the following multiple choice MCCB.
Circuit breaker protection can be divided according to purpose and distribution lines to use, motor protection , the protection of lighting circuits and leakage protection , etc. with . Commonly used DZ5, DZ15, DZ20, DW15, DW17 -series products.
1 , motor protection circuit breaker selection principles
1 ) long delay current setting equal to the rated motor current.
2 ) instantaneous setting current : For protection cage motor circuit breaker , instantaneous tuning current is equal ( 8 to 15 ) times the rated motor current , depends on the type, size and condition of the protective cage starter motor . For wound rotor motor protection circuit breaker instantaneous setting current equal to ( 3-6 ) x rated motor current , depends on the type , capacity and start-up conditions to protect a wound rotor motor.
Return time 3 ) 6 times long delay current setting is greater than or equal to the motor starting time . Light and heavy loads when you press start , you can choose to return time 1s, 3s, 5s, 8s, 15s in a file.
2 , the circuit breaker specifications of Table Info
According to the capacity or the rated current of the motor , you can find out which is equipped with a circuit breaker specifications . For example, a Y160M-4, 11kW electric motor from Cheat Richard should be equipped with DZ5-50 type , heat release rated current of 25A circuit breaker.
3 , the circuit breaker trip setting current speed calculation formulas
" Instantaneous electric motor , kW 20 times ."
" Heat release, according to ratings"
The above formulas refers to the control circuit breaker to protect a 380V three-phase cage motor , the magnetic trip setting current instantaneous action , according to " 20 times the number of kW " choice . For heat release, press the motor nominal current .