Q. We currently have a situation with our high voltage rectifiers
overheating. We have 4 chrome lines. Each Chrome line has 4 rectifiers on
each line. We plate solid rods that very in size from 12.5mm-25mm. Our
chrome line #4 (10years old) is giving us our main issue with heat. The rod
size that is ran down this line consists of 18mm, 20mm, 22mm, 25mm. A quantity
of 20 rods are ran at one time. Our rectifiers are on a platform and the
legs on our rectifiers are about 4" tall, this is where the fan is that
draws the air up through the rectifier to cool it internally. The main
problem is they are drawing warm to hot dirty plant air through the
rectifier and not cooling them properly. Can you give me any alternate
cooling sugestions for our rectifier issue? We really don't want to purchase
all new rectifiers due to the cost.
A. Heat in the plating area is a common enemy. It affects everything
including the coating performance if the bath or the rectifiers get hot. It
can also lead to everything heating up at the plating line and eventually
racks and parts begin to over heat. Sometimes bussing and tooling are
inadequate and the heat generated at the plating tank can be transferred
back to the rectifiers, causing lots of problems. It might be beneficial to
bring in an expert at some point if you are not able to resolve this by
It's not uncommon to see this in plating shops. Dirt and debris can find it's
way in thru the air intake openings. Most air cooled units use expanded
metal screens with quite large holes. Designers of course more concerned
about the equipment running cool than screening out solid particles. I'll
send a couple pics of a shop I recently did some consulting work for. They
had similar problems... and as the photos show, this kind of electronic gear
is easily neglected.
Quick fix? There are a few. If you are unable to change the environment
around your power supplies, you might be forced to replace the air cooled
units with water cooled. Short of changing cooling systems on the current
units or buying new water cooled units, I would probably recommend having a
fabricator outfit the bottom (intake openings) of your rectifiers with a
bracket or framework to hold a flexible air filter. This material comes on a
roll or in precut sections. The operator can simply pull out the old and pop
in a new piece, or possible wash the old filters out and reuse. You can buy
air filter material in numerous grades. This filter would function much the
same as the air filter on a home heating & air conditioning system. Be
careful to use the appropriate type of filter material that captures most
particulate matter but will not restrict the air-flow.
Secondly, Its important to keep the "heat sinks" clean. These are the
silver, iridescent yellow or nickel plated coolant blades inside the
rectifier bussing near fuses and diodes. This equipment helps to dissipate
heat. A thin coating of dirt on these can reduce the cooling efficiency by
more than half.
A third suggestion is to study the options of bringing in some additional
cool air into the space that houses your power supplies. You could do this
in several ways, if you have a basement, creating an updraft system by
selectively opening up the floor and bring air vents up from the basement.
This can also be accomplished by venting in cool air from outside to the
area by way of flexible industrial tube vents from above the rectifiers...
You could also go directly into the rectifier cabinet with a rigid cold air
vent and draw cooler air in from above the units avoiding the floor
altogether. In some hot climates some shops actually bring in outside air
through a filtered air make up system avoiding using shop air all together.
A forth suggestion might be to build an enclosed room around the units and
air condition the space, or at least erect a wall between the power supplies
and the plating line. This is actually a common design practice we've used
in designing new plating facilities for many years now. Separating sensitive
electronic gear from the shop environment will add years to the life of the
I can find out what the filter material is called and who might supply it if
you need further assistance.
Finally, plating rectifiers should be on a routine maintenance schedule and
periodically be shut down, inspected, cleaned, vacuumed out and wiped down
on the inside as well as having the meters or digital readouts checked under
a "load" to confirm accuracy. This is a good opportunity to check the
rectifiers for "ripple" and other general conformance issues.
I would like to hear more about your process and production concerns if you
want to discuss, please feel free to contact me anytime.