Is there any DIY circuit which can measure earth leakage current in mA?

Replies

• 

  Happy Chap

  Hi wkyong,
  
  Are you wanting to measure AC or DC currents? If you want AC, you can use a current transformer, and multimeter, but most current trannys require you to break the wire to install them over it, then reconnect the wire and leave the transformer there. Otherwise, you can use a "clamp tester" type meter, which is a current transformer that opens up to place it over the wire, its portable, and many now use a Hall Effect IC for measuring both AC and DC. I have ordered one on Ebay, which is supposed to do AC and DC, and it cost me less than 50 bucks delivered to my door. I wouldn't muck around building a circuit for that. I should have it in a week. It only measures down to 0.1 amp though, but there are better meters around, that measure down to milliamps, but you pay more for them.
• 

  d_vipul

  Hey wkyong,
  
  tong meter or clamp meter is a better option to measure earth leakage current up to 250A but it is not safer for currents above 250A.....
  
  For above 250A currents you have to use Current transformer in co-ordination with ammeter.....
  
  Hope this helps you.....
  
  Regards,
  VIPUL
• 

  Happy Chap

  d_vipul

  Hey wkyong,
  
  tong meter or clamp meter is a better option to measure earth leakage current up to 250A but it is not safer for currents above 250A.....
  
  For above 250A currents you have to use Current transformer in co-ordination with ammeter.....
  
  Hope this helps you.....
  
  Regards,
  VIPUL

  Why Vipul? With a tong tester, you are not interrupting the earth cable at all, and the cable is (theoretically) at near earth potential. I'll happily wrap a tong tester around a cable to a big motor, carrying 800 or more amps, and at 240 or 380V potential, so why is it not as safe with an earth conductor. Unless the current transformer has a split core, it is necessary to disconnect the cable to install the CT. I would think it much safer to leave the earth cable alone, and just wrap a tong tester around it, irrespective of the current flow in it.
  
  Just curious, maybe you have a good reason for your statement, and maybe I'll learn something too.
  
  Cheers, Mike.
• 

  d_vipul

  Hey Happy,
  
  You are right Happy but sometimes it may be risky. You can use Clamp meter for a stable system But when their is a fault it may be hazardous to the person who is carrying Clamp Meter......
  
  Actually it is my experience, One of my friend got shock when he was testing a motor with Clamp Meter He was just saved that time due too his luck thats why I am telling you this.....
  
  Got you Happy????
  I hope you will get this.......
  
  As much as possible stay away from a LIVE SYSTEM.......
  
  Regards,
  VIPUL
• 

  Happy Chap

  Hey Vipul, That's rather difficult where I work. We have voltages uo to 256kv, and currents up to 350KA (continuous, not spikes or peaks), and our electricity bill is about $2M a day. And I'm in maintenance, working with it most of the day.😎
  
  Cheers, Mike.
• 

  d_vipul

  Hey Happy,
  
  Prevention is always better than cure..........
  
  Take care........
  
  Regards,
  VIPUL
• 

  Happy Chap

  Thanks Vipul, yes, safety is an absolute No. 1 priority at our establishment, to the point of being painful.
  
  Wkyong, How are you going, have we been of any help here?
  
  Cheers, Mike.