My Floor Buffer Trips Circuit Breakers...
I see this issue literally every day and it's about time I
blog about it on our website.
The typical problem I hear is "As soon as I pull the
trigger, the wall circuit breaker trips…" or "When I pull the
trigger the unit doesn't start fast and doesn't have any power…"
If the unit is a high speed burnisher, or low speed high
torque unit, then the problem is a rectifier located in the top of the
motor. ALL burnishers of 1000 RPM or more are AC motors at the wall, but
convert the AC current to DC electrical power inside/near the motor. Why
use a DC motor? Simple, they deliver
more torque to turn the pad. If you
don’t have a DC motor, jump to the AC motor section….
If the unit immediately trips a circuit breaker, the
rectifier has blown a short. If the motor starts, but has no power then
one half of the bridge has blown. A sample of this part is located at
this by clicking here, and in fact you can order the part for any manufacturer's
machine from that link if yours looks like it.
Where is it located? Typically inside the motor
itself. RARELY do you have to disassemble the motor itself. Some
older models located the rectifier on the base of the buffer external to the
motor. You may have to remove housing cover(s) to revel the part.
IT IS CRITICALLY IMPORTANT TO FOLLOW THE NEXT INSTRUCTIONS!
When changing the part, you must align the new part in the same orientation as
the old part with the notched corner in the same position. Change only
one wire at a time, if you fail to connect them correctly you will damage the
motor. The next step is CRITICAL -- before you install the new part, stop
at the local auto supply store, Radio Shack, Best Buy (in the computer parts
department) or the like and obtain a small amount of thermal transfer compound
(sometimes called heat transfer compound). This looks a lot like and has
the same consistency as toothpaste. On
the back bare metal side of the rectifier, place a “pea” sized amount of compound,
then reattach the rectifier to the mounting point. Do not over tighten the screw. FAILURE TO USE THE HEAT COMPOUND WILL CAUSE
PREMATURE FAILURE OF THE PART.
Reassemble everything and you’ll be buffing again.
I get asked why this might have blown? There are many reasons why that influence the
failure, but it boils down to heat.
Using the machine on extension cords, bearing down on the machine,
things that increase the electrical load on the machine will cause the
rectifier to deliver more power to the motor increasing the heat inside the
part. If the heat cannot be displaced
fast enough, the part will fail prematurely.
AC MOTORS –
These motors are more difficult to locate the source of the problem. AC motors will ALWAYS have capacitors on them
to assist in starting and running. Some
motors have one start, and others have two depending on the design of the
motor. Most AC motors have a start
switch that operates on the turning of the armature. This switch is under the motor's cover on top of the armature. To replace
it you will need to disassemble the motor.
The typical symptom of this switch stuck is pulling the trigger, the
motor humming or turning slowly, the lights dimming, and then the breaker
tripping. The contact points can
sometimes be cleaned in a pinch with high grit sand paper, but the switch
contacts arc when they operate and will eventually degrade, the switch must be
replaced.
There are often different combinations of carbon brushes in
the motors. It is important to inspect
them and the contact areas, if you see any damage the parts must be
replaced. They are easy to replace and
will extend the life of the motor dramatically.