Electrical Shock from Motor Body Causes, Safety, Prevention
Hey, in this article we are going to know what are the causes or reasons when we get an electrical shock from a motor body. There are so many reasons behind we get an electrical shock when touching the motor metallic body. Also, we will know what safety measures we should take to avoid these types of problems. Actually this problem I have faced in a company during daily preventive maintenance. So let's go to know.
Reasons behind Electrical shock from Motor Body
1. Insulation Damage
We know that conductors used for motor winding are coated with insulating materials like Varnish to maintain insulation between each conductor and conductor to slots or motor body. Each slot for coil also laminated by insulation like mica paper or other laminated paper.
When coils are inserted into slots then also slot insulation provided. These all insulation arrangements ensure the complete insulation between the current-carrying part or Live part of the coil and motor metallic body and frame.
So any insulation damage or failure can cause the touching of the current-carrying part of the coil to the motor body or frame. Insulation failure may happen due to the overheating of the motor or any mechanical injury.
So, this is the common reason which mostly happens which causes to get electrical shock from the motor body.
2. Improper Terminal Connection
Although motor body, frame, terminal box all are painted by insulating paint, then also during terminal connection of the motor if any conductor touched to the motor metallic part then we will get an electrical shock from the motor body. So improper terminal connection also can cause to get an electrical shock from the motor body.
Even if you connect the power terminal to the earthing terminal of the motor by mistake then also this problem will happen.
3. Other Reason
The motor body, frame always should be dry. Any contacts of water also can create leakage current from the current-carrying part to the body or frame. This mostly happens with water pumps.
First, turned off the motor. Disconnect the motor from main power supply. Check the earthing connection. Check continuity between phase to motor body or phase to earth by a multimeter. If continuity came then check anywhere live conductor touched to the motor body. Check everything including insulation, connections, etc. Check and repair until your multimeter or megger shows the infinity resistance between the motor body or live terminals.
The first and most important safety measure is the earthing of the motor body. During the installation of an electric motor, the metallic body of the motor should be connected to the earth. When any live part of the coil touched to the motor body or any leakage occurs it will bypass through the earthing. Install double earthing connection if required.
When connecting motor terminals to the power supply, a proper connection should be given means no string of the conductor should be touched to the motor metallic body. Or there should be no direct connection between the phase terminals and earthing terminals. Even it is not preferred the direct connection between neutral wire and earth wire within the motor.
Proper insulating paint should be done on the motor body, frame, and terminal box.
High level insulation should be used for coil, motor slots, etc.
Daily preventive maintenance should be done properly including checking of hotness of the motor, lubrication, cooling, noise, etc.
Don't touch the body of the motor by bare hand, first, check with line tester, then you can touch to check hotness, vibration, etc.
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3. Other Reason
The motor body, frame always should be dry. Any contacts of water also can create leakage current from the current-carrying part to the body or frame. This mostly happens with water pumps.
Most of people think the earthing fault is the main reason behind the electrical shock from the motor body, but it is not true. Yes, it is true that motor body earthing is the main safety measure to prevent this problem.
How to Solve this Problem?
First, turned off the motor. Disconnect the motor from main power supply. Check the earthing connection. Check continuity between phase to motor body or phase to earth by a multimeter. If continuity came then check anywhere live conductor touched to the motor body. Check everything including insulation, connections, etc. Check and repair until your multimeter or megger shows the infinity resistance between the motor body or live terminals.
Safety and Prevention
The first and most important safety measure is the earthing of the motor body. During the installation of an electric motor, the metallic body of the motor should be connected to the earth. When any live part of the coil touched to the motor body or any leakage occurs it will bypass through the earthing. Install double earthing connection if required.
When connecting motor terminals to the power supply, a proper connection should be given means no string of the conductor should be touched to the motor metallic body. Or there should be no direct connection between the phase terminals and earthing terminals. Even it is not preferred the direct connection between neutral wire and earth wire within the motor.
Proper insulating paint should be done on the motor body, frame, and terminal box.
High level insulation should be used for coil, motor slots, etc.
Daily preventive maintenance should be done properly including checking of hotness of the motor, lubrication, cooling, noise, etc.
Don't touch the body of the motor by bare hand, first, check with line tester, then you can touch to check hotness, vibration, etc.
Thank you for visiting the website. keep visiting for more updates.
Electrical Shock from Motor Body Causes, Safety, Prevention
Reviewed by Author
on
July 29, 2020
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Reviewed by Author
on
July 29, 2020
Rating: