What is the reason for the leakage of electricity from the refrigerator shell? How to deal with electrified refrigerator shell
After the beginning of autumn, the weather is still warm. When I came home from work last night, I wanted to get an ice cream to cool down, but as soon as I touched the refrigerator, I felt a current run through my hand. After dodging it, I immediately turned off the electric switch, thinking how could the refrigerator shell have electricity? I still tremble when I think about it now! Most of the leakage in refrigerators is caused by the aging or damage of the parts due to the excessive use of the refrigerator, which causes the condensation water in the refrigerator to form a loop. In addition, during transportation of the refrigerator, components collide due to vibration, and the insulation of the wires is damaged. May cause leakage.
In fact, the current on the refrigerator outer shell is an inductive current, which belongs to the normal charging of the refrigerator. This inductive current is relatively small and does not pose a threat to our personal safety, so don’t worry too much. However, in addition to the normal induction electricity of the refrigerator, the electrification of the refrigerator shell may also be caused by its leakage problem. If the refrigerator leaks electricity and leads to electrification, and accidentally touches it without knowing it, you will feel electric shock, which will pose a great threat to our personal safety!
( 1 ) Compressor leakage
Generally, due to the long use of the refrigerator, the insulation layer of the motor windings ages and falls off, causing leakage. During maintenance, a 500V/500M Ω megohm meter can be used to measure the resistance between the winding and the casing. Normally, it should be greater than 2M Ω. If it is 0 Ω, the casing should be opened for inspection. Focus on checking whether the insulation layer of the winding leads is damaged, resulting in exposed copper wires and contact with the casing, causing leakage. If the above phenomenon exists, use mylar to wrap the damaged area to avoid direct friction with the casing. If the insulation layer of the enameled wire is found to be peeled off, remove it and re-dip it or replace the motor.
( 2 ) Leakage from the thermostat
The phenomenon of leakage from the thermostat is: when a human hand touches the box, there is a hemp inductance, but the compressor is running normally and the cooling inside the box is cooling normally. The voltage between the refrigerator and the “ground” is high (greater than 36V or even close to the mains voltage). If a 500V megohmmeter is used to measure the compressor winding and motor control circuit respectively, and the insulation resistance between the refrigerator lighting circuit is above 2 M Ω, it means that the thermostat is leaking. Because the thermostats of most refrigerators are installed on the inner wall, changes in the temperature inside the box will cause dew condensation around the thermostats. When condensed water flows into the thermostat, the resistance value between the thermostat’s electrical contacts and the box drops, causing the box to become electrified. The way to eliminate it is to defrost it regularly and often wipe away stagnant water in the refrigerator to prevent condensed water from flowing into the thermostat. At the same time, clean the thermostat Bakelite frame and the surrounding dirt frequently, because the dirt will also generate leakage after absorbing moisture. If the thermostat is poorly insulated, it should be replaced.
( 3 ) Leakage of moisture-proof wire
The leakage of moisture-proof wires is generally common in refrigerators with a long life. It is manifested by the frequent turning on and off of the overload protection relay after the power supply is turned on. The compressor cannot start, the box is electrified, and there is a hemp inductance when touching by hands. The power supply voltage is normal, and the DC resistance of each winding of the compressor is normal with a multimeter R × 1 gear. There is no obvious short circuit between each winding and the ground. Check that there are no obvious abnormalities in the temperature control circuit and the lighting circuit. At this time, it can be judged that the moisture-proof wire is aging or the insulation layer is damaged and leaking electricity. First, disconnect the circuit connected to the wire, and measure that the resistance value between the two cores of the wire is below 1M Ω (normally it should be infinite), which means that its insulation resistance is low, leakage occurs under the influence of external factors such as condensation, and the compressor cannot operate normally. The protective relay is repeatedly turned on and off. At this time, insulating conduits can be used to cover the moisture-proof wires. It is best to remove the old wires and replace them with new ones with rubber insulated wires.
(4)The connector is loose, causing poor grounding and leakage
If it is found that the box has hemp inductance, but the insulation resistance between the compressor winding and the casing is greater than 2 measured with a megohmmeter. 5M Ω. On the premise of eliminating the above faults, this situation indicates that the insulation between the circuit and the box is normal. It is estimated that the fault site is in the power socket. For example, the ground wire of the socket is deformed and loose, causing the refrigerator metal shell to not be truly grounded and causing leakage. After this happens, you only need to repair the socket wire piece to make it in good contact.
( 5 ) Induced leakage
After the refrigerator is started, if the cooling and control components in the box are normal, but the electric feeling is numb when touching the box with your hands, it means that there is inductive leakage in the refrigerator. If you use an electric test pen to check that the neon bubble shines, it means that there is a serious leakage in the refrigerator.
The reason is generally: Since the control circuit of the refrigerator compressor and the lighting circuit in the refrigerator pass between the shell and the inner wall of the box, if the insulation of the wires ages, the refrigerator has no reliable ground wire. When a person touches the box, It will produce hemp inductance. The elimination method is to reliably ground the metal shell of the refrigerator. Be careful not to connect the refrigerator ground wire to the gas pipe or water pipe.