The electric control valve accessories malfunction and cause analysis

- - - - - - - - - - - - : electric control valve accessories have front magnetic amplifier, regulating valve and so on, here we mainly talk about electric regulator proper use and maintenance of the servo amplifier. Daily professional for its maintenance can not only improve the reliability of the process control, also can increase the service life of electric control valve, Shanghai mountain meter below the failure reason and solution for the following detailed introduction of electric control valve operation of the front magnetic amplifier is each part may have the following four case ( ) Front magnetic amplifier (1) when no signal input, the double take magnetic amplifier output through the adjustable potentiometer W to zero. Cannot be zero could be A desoldering, transformer W or damaged. B, R, R, and electrolytic capacitor C, C virtual soldering or desoldering. C, diode D ~ D virtual welding or damage. D, the offset current is not normal. E, asymmetric ac winding. (2) with the input signal, but no output or output may be asymmetric, transformer B for asymmetric ac voltage of the secondary winding current. B, a change in the value of R and R, damage of electrolytic capacitor C, C. C, ac field winding short circuit. D, diode D ~ D the individual pipe damage or virtual welding. ( ) The trigger input, including the trigger on the oscillograph screen should have the pulse signal, to change the input signal polarity, the other side of the trigger pulse signal. Two groups of trigger pulse number and amplitude should be basically the same. Otherwise there are several ways. (1) no input signal ( Front magnetic amplifier under normal working state) A trigger pulse, the output end, may be A trigger pulse output A, one side of the triode is damaged, or is c, e virtual welding. B, R, R, R, R value has changed. (2) with the input signal, the output end without A trigger pulse, is likely to be A, without the triode, knot on one side of the output pulse tube damage. B, no one side of the output pulse pulse transformer primary or secondary circuit or short circuit. C, on one side of the output pulse diode ( D/D) Short circuit. (3) the output trigger abnormal has the following several kinds of phenomenon A, no signal when the trigger pulse output, the two groups after add signal normal again, probably electrolytic capacitor C or C virtual welding. B, started working on both sides of the trigger output is normal, after a period of time, the output pulse gradually disappear, may the knot tube has a problem. C, positive and negative pulse output appear, may be a diode D and D are breakdown or virtual welding. ( ) After the inspection and maintenance, under the condition of control loop trouble-free servo amplifier should be able to work properly. Or has the following two conditions (1) there is no input signal, the output voltage ( Voltage close to VAC) Could be A, silicon controlled SCR, damage of SCR. B, capacitance C, C is punctured. (2) with the input signal, the output signal or output voltage is low, may be in A, diode D ~ D have been breakdown. B, SCR silicon controlled rectifier, damage of SCR. Electric control valve servo amplifier normal working state is likely to have the following three conditions ( ) No input signal, the output voltage not to be. ( ) Open loop dead zone current & amp; le; & mu; 一个( Ⅱ type for & amp; mu; 一) 。 ( ) The input signal > & amp; mu; 一个( Ⅱ type for & amp; mu; 一) When the output load voltage for? V ~ ? AC。 ( ) Basic symmetric output voltage.