What are the frequent problems with relays and Auto Relay in use?
The range of use of relays is now more and more extensive, the more frequently used,the longer the time, there will be some problems, then on relays and automatic relays The more common problems are as follows:
The contact of the relay is faulty, which is more common. For most faults, about 70% of the faults occur on the contacts. It is important to select all the relay contacts.
First, the choice of AC and DC electromagnetic relays Almost all AC relays are caused by the humming caused by the armature vibration. When the voltage on the relay coil (or current) When the specified action value is not reached, the armature flutter will cause the contact to shake. If the contact is connected to the inrush current load, the arc caused by the chatter may be touched.
The point is melted or welded. Second, the relay operating voltage selection When the relay works, the coil should apply the rated
working voltage (current) instead of the suction voltage (current), thus enabling The electrical coil voltage (or current) has a mechanical voltage shock or ambient temperature rise when the power supply voltage (or current) fluctuates or the relay is used. The insurance margin of work. The suction voltage (or current) is only a parameter that the manufacturer limits the sensitivity of the relay and evaluates it.
The relay has different release voltages The bigger the better. When the relay is released, if the leakage current in the coil circuit is too large, the relay will not be released reliably. Third, the selection of relay load capacity and failure analysis relays will be the following kinds of loads when in use
1, capacitive load
The charging current of the capacitive circuit, the short-circuit discharge current starts at a large time,when charging or short-circuiting, the contact may be severely ablated due to too much charging current or Welding failure. In use, if the current limiting capacity can be connected in series according to the size of the capacitance,the hazard can be eliminated.
2, incandescent lamp load
Since the cold resistance of the tungsten wire in the incandescent lamp is very small, the inrush current at the instant of turn-on is as high as 15 times the steady-state current. Such a large inrush current will make the contact quickly. Corrosion, even welding failure.
3, motor load
The input impedance is very small when the motor is stationary, so the surge current is very large just after starting.
Due to the difference in motor load, its startup time has It can be short or long, so the startup surge current lasts for the same amount of time. In addition, the relay contact is used as the motor opening and closing switch, and the shutdown is continued. The electrical appliance must withstand the arcing caused by the high induced back voltage shock of the motor windings, so the insulation resistance level between the contact groups and the ability to withstand overload must be There
is ample surplus.
For more information on relays and automatic relays, please visit the official website of Wenzhou Anxun Electric Co., Ltd.: https://www.nicerelay.com.