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This article will focus on the circuit in the electric actuators parts. The circuit of the electric actuator parts mainly includes: driver module hardware circuit, power supply module hardware circuit, control module of hardware circuit and protection module hardware circuit, man-machine interface module hardware circuit. The drive circuit of electric actuator parts is composed of rectifier circuit and filter circuit.
According to the requirements of electric actuator parts, remote control power uses 24 v dc. Remote control module allows the staff to control the electric actuator working conditions in the control room. Therefore, the remote control electric power supply is also important in the electric actuator parts but it chooses LM7824 as its voltage regulator. The signal of remote control is sent by the micro controller to prevent the microcontroller from being broken in the overvoltage work, therefore an isolation measure should be taken between the remote control and remote control circuit power supply.
In the electric actuator parts, remote monitoring control adopts the manner of relay monitoring. When the remote control work is working normally, the REMOTE end is in low level with photoelectric coupler conduction and Q6 conduction and the power supply will be controlled through REMOTE end. If there were errors in the remote control and it can't work normally, one convenient way is to shut down the remote control module and that is why the jump line protection is especially set up in the electric actuator parts.
If the jumper wire moves to the D10 route, you can shut down the remote control, which provides the security for the remote control. Since the REMOTE end is directly connected into the microcontroller, a photoelectric coupler is to be added into the electric actuator parts for photoelectric isolation, in order to prevent the micro-controller from being burnt out. Photoelectric isolating device is a converter that puts the light emitting devices (such as light emitting diode) and photosensitive device (such as light activated triode) together and realizes the electricity, light, electricity isolation by the light coupling. Optoelectronic isolator can not only transmit signals but also can effectively restrain interference sources. Excellent characteristics of photoelectric isolation have provided the convenient and reliable security for us to make isolation and anti-interference design, making the design simple and reliable. However, we should pay attention to some details that are related to the electric actuator parts, otherwise they will backfire.
We should be paid attention to the following problems in the use of photoelectric isolation technique in terms of electric actuator parts:
(1) The same series of different series of optoelectronic isolator CTR (current transfer ratio) are different. When we are making choice, we need to choose the proper model according to design requirements;
(2) To make a selection is to consider the optoelectronic isolator maximum withstands voltage value of the output side. The working voltage is not allowed to exceed this value in the circuit, and there must be some remaining value. We also need to consider about the surge values and can apply a diode in parallel to surge interference when it’s necessary;
(3) We need to pay special attention to the output side of diode reverses voltage value. When it’s necessary, we can reverse parallel a diode on the input side of the diode to protect the pneumatic actuators;
(4) The current transfer ratio is influenced by input current. So you need a suitable current value to obtain the corresponding current transfer ratio.