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"Performance of an SCR rectifier vs Tap Switch"





April 23, 2010

I have changed my old tap switching rectifier for a scr rectifier but the performance is not the same, for nickel the parts seem to delay more to achieve the same results and when you chrome the parts didn't show the same reaction as with the tap switching rectifier, the older was only 600 amps, this one goes up to 950 amps but the results from the other were sometimes better with less current.

Can be this caused by a too high ripple?

Daniel Hernandez
plater - Bucaramanga Santander Colombia
^


April 29, 2010

Step one is to calibrate both the voltmeter and the ammeter at several loads. Check at the bus bar and at the power supply. Clean and tighten all connections from the unit to the tank.
Power supplies that I used either had chokes or were three phase, so ripple was not a factor.
Nickel is not normally bothered by ripple, chrome is.

James Watts
- Navarre, Florida
^


May 3, 2010

Thanks

Looks like there were some kind of problem with connections after cleaning and maintenance from the supplier the problem disappeared

the vendor added a big choke it is supposed to help with the ripple.

it is really a need for decorative chrome?
How does it improve the appearance of the deposit?

DANIEL HERNANDEZ
- Bucaramanga, Colombia
^


First of two simultaneous responses -- May 4, 2010

Yes you want the chokes to control the ripple. <1% is a good goal for hard chrome. Some people say that <5% is okay, but the lower the better.

Jon Barrows
Jon Barrows, MSF, EHSSC
Independence, Missouri
^


Second of two simultaneous responses -- May 5, 2010

In my experience the most common problem with ripple in power supplies in hexavalent chromium plating is a hazy white film in the deposit. In the UK (and I guess elsewhere) it is called "white washing". It can be caused by many things. When it occurs, the first thing to check is whether one phase of a 3-phase rectifier has been lost as this would increase the ripple in the supply.
The choke, if of adequate inductance, would reduce the ripple. One feature of a SCR power supply is that the ripple decreases as the voltage/current is increased.

harry_parkes
Harry Parkes
- Birmingham, UK
^

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