Troubleshooting ripple

Discussion in 'General Electronics Chat' started by D.T., Aug 15, 2014.

  1. D.T.

    Thread Starter New Member

    Aug 15, 2014
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    0
    Noob here. :D

    We have a Kocour model #5-C 0-12V 5A rectifier for plating that has 11% ripple. It's fairly corroded and I went through most of the connections last night to help get the ripple down to 5% or less.

    I'm using a Fluke scopemeter and can't seem to get rid of the 20mVAC of ripple at the output. Tested the diodes and capacitor they seem OK. I'm not the best electronic tech but I'm trying to learn.

    Thanks in advance,
    Dave
     
  2. BR-549

    Well-Known Member

    Sep 22, 2013
    2,006
    394
    If you are using florescent lights in the facility, you are broadcasting ripple. The ground lead on the scope might be picking it up. Wrap the ground probe lead around tip of probe to shorten up. Did the plater work normally recently? Disconnect the plater. Attach appropriate resistive load(~2.5 ohm, 10 watt) to power supply. If ripple is gone....plater racks or hangers are picking it up. If ripple is still there, buy off the shelf 12 VDC, 20 AMP, switching power supply.....they are cheap. Get 20 amp, so supply is lightly loaded. What are you plating? Worked on copper, nickle, and chrome plater 45 yrs. ago. Can't recall ripple problems.
     
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    Specs say:

    Filtered DC current source
    Output 0-12 volts DC with less than 3% ripple

    3% of 12V is 360mV. What is the problem?
     
    BR-549 likes this.
  4. D.T.

    Thread Starter New Member

    Aug 15, 2014
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    I understand what you are saying. Our certification co. says there is 11% ripple. I found the 22mVAC with the scope.

    The way I'm calculating ripple is ACmV divided by DCmV times 100 equals ripple %. I am taking the voltage values from across a 50mV 50A shunt under load. Since the ripple is there under load only I assume there is a bad connection somewhere.

    Am I doing something wrong? I can get the values the cert company came up with later tonight. The rectifier is for a hull cell testing equipment for copper plating in the lab.

    Thanks guys.
    Dave
     
  5. alfacliff

    Well-Known Member

    Dec 13, 2013
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    one of our plating rectifiers went to rippling a while back, one of the smaller ones, only 5kA. it turned out to be a bad scr. 480 v3ph in and scr's to adjust the output. while looking up the specs for ripple on plating aircraft parts, the percentage wasnt really very low, not having the bubbler on to keep the surfaces clear made mor difference to the finish.
     
  6. D.T.

    Thread Starter New Member

    Aug 15, 2014
    4
    0
    I just repaired a 3ph 0-8VDC 300A rectifier for nickel plating. It had 17% ripple. I put a large shunt on it and cranked up the amps. Found sparking at a connection for the transformer secondary. Tightening a loose bolt fixed it. It dropped a phase to get the high ripple %.

    I emailed Kocour and they said to send it in for repair. No help there.
     
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