Why do electric actuators always show over torque？

  電動執行器為什么總顯示過力矩？如何安全使用電動執行器呢？中英合資天蝶閥門來給大家詳細講解。

  Why do electric actuators always show over torque？How to use electric actuator safely?The Sino-British joint venture Tandy Valve will explain it to you in detail.

  當電動執行器的規格確定之后，其控制轉矩也確定了。當其在預先確定的時間內運行時，電機一般不會超負荷。但如出現下列情況便可使其超負荷：

  When the specification of the electric actuator is determined, the control torque is also determined.When it runs in a predetermined period of time, the motor is generally not overloaded. However, it will be overloaded if : 

  1.電源電壓低，得不到所需的轉矩，使電機停止轉動。

  1. Low supply voltage, can not get the required torque, so that the motor stops turning.

  2.錯誤地調定了轉矩限制機構，使其大于停止的轉矩，而造成連續產生過大的轉矩，使電機停止轉動。

  2. The torque limiting mechanism is set incorrectly so that it is greater than the stopping torque, resulting in the continuous generation of excessive torque, so that the motor stops turning.

  3.如點動那樣斷續使用，產生的熱量積蓄起來，超過了電機的容許溫升值。

  3. If the intermittent use of the point move, the heat generated by the savings, exceeding the allowable temperature appreciation of the motor. 

  4.因某種原因轉矩限制機構電路發生故障，使轉矩過大。

  4.For some reason, the circuit of torque limiting mechanism breaks down and the torque is too large.

  5.使用環境溫度過高，相對地使電機的熱容量下降。

  5. The use of ambient temperature is too high, relative to the heat capacity of the motor decreased. 

  以上是出現超負荷的一些原因，對于這些原因產生的電機過熱現象應預先考慮到，并采取措施，防止過熱。
  These are some of the causes of overload, for these reasons the phenomenon of motor overheating should be considered in advance, and take measures.Prevent overheating.

  過去對電動執行器電機進行保護的辦法是使用熔斷器、過流繼電器、熱繼電器、恒溫器等，但這些辦法也都各有利弊，對于電動裝置這種變負荷的設備，可靠的保護辦法是沒有的。因此必須采取各種方法組合的方式。但由于每臺電動裝置的負荷情況不同，難以提出一個統一的辦法。但概括多數情況，也可以從中找到共同點。

  In the past, the electric motor for electric actuators was protected by fuses, overcurrent relays, thermal relays, thermostats, etc, But these methods also have their advantages and disadvantages, for the electric device such as the variable load equipment, absolutely reliable protection method is not available. It is therefore necessary to adopt a combination of approaches. However, due to the different load conditions of each electric device, it is difficult to propose a unified approach. But in most cases, common ground can also be found.

  采取的過負荷保護方式，歸納為兩種：

  There are two types of overloading protection:

  1．對電動執行器電機輸入電流的增減進行判斷；

  1. Judging the increase or decrease of the input current of the motor in the valve electric device;

  2．對電機本身發熱進行判斷。

  2. Judge the heating of the motor itself.

  上述兩種方式，無論那種都要考慮電機熱容量給定的時間余量。如果用單一方式使之與電機的熱容量特性一致是困難的。所以應選擇根據過負荷的原因能可靠的動作的方法——組合復合方式，以實現全面的過負荷保護作用。

  The above two methods, regardless of the kind of motor heat capacity should be considered a given time margin. It is difficult to match the heat capacity characteristics of the motor in a single way. So should choose according to the reason of overload can reliable action method-combination compound way, in order to realize the comprehensive overload protection effect.

  中英合資天蝶閥門生產的電動執行器電機，因其在繞組中埋入了與電機絕緣等級一致的恒溫器，當到達額定溫度時，電機控制回路便會切斷。恒溫器本身熱容量是較小的，而且其*特性是由電機的熱容量特性決定的，因此這是一個可靠的方法。

  The special motor for electric actuator of the Sino-British joint venture Tandy Valve, because it has a thermostat embedded in the winding, which has the same insulation level as the motor, reaches the rated temperature.The motor control circuit will be cut off. The thermostat itself has a smaller heat capacity, and its time-limited characteristic is determined by the heat capacity characteristics of the motor, so this is a reliable method. 

  電動執行器過負荷的基本保護方法是：

  The basic protection methods for overload of valve electric devices are:

  1.對電機連續運轉或點動操作的過負荷保護采用恒溫器；

  1. Use a thermostat for over-load protection of the continuous operation or point operation of the motor;
  2.對電機堵轉的保護采用熱繼電器；

  2. Use thermal relay to protect the motor;
  3.對短路事故采用熔斷器或過流繼電器。

  3. Use fuses or overcurrent relays for short-circuit incidents.