The KBs with a flat (aluminum) mounting plate mount nicely when
fastened to the back of a metal enclosure (heatsink compound applied).
The metal enclosure provides the additional cooling surface.
An optional procedure is to add a large finned heatsink to the back of
the metal enclosure to provide even more heat dissipation (assuming
ambient air is cool).
With the enclosure closed or sealed, the module stays clean and cool.
The KB website may have more info related to mounting and ventilation,
and other drive manufacturers' websites may also.

Generally, the circuit board components don't need cooling in normal
operating conditions, but the components that are fastened to the
heatsink need to have their heat dissipated away from them, into the
area's natural air currents.
With a factory installed finned heatsink, the design includes adequate
heat dissipation from the fins, in most cases, assuming that there is
some air movement over the fins.

A plastic enclosure wouldn't be my first choice for mounting a
power-dissipating circuit, but a small fan for ventilation would be an
appropriate measure.
If you were to ask opinions of whether pushing air in, or drawing air
out, is more effective, I'm sure it would be a lively discussion. I've
seen both of those methods strongly insisted and defended before.

I believe your KB drive has better over-current and current surge
protection than your other drive had. The manufacturer's
installation/setup adjustments should cover the limit adjustments.
Having a amp meter (or a heavy duty current shunt with a meter) to
monitor the load current, for a couple of test runs will allow you to
make sure that the drive is operating within it's intended range.

A GE drive that I have, came with a finned heatsink, but only the SCR
pack was attached to the heatsink, so I cut a clearance hole in the
back of the enclosure, fastened the heatsink to the outside rear
surface of the enclosure, and then re-mounted the SCR pack to the
heatsink as it had been originally mounted. This method ensures that
the circuit is kept clean, and that the power device has better heat
dissipation characteristics, as the metal enclosure effectively
increases the heatsink area.

The KB drive I have, has more than just the power device attached to
the finned heatsink, so I won't be using the same method to enclose it.
When I get around to using it, I'll probably just install it in a
ventilated enclosure, away from sources of stray conductive material. I
don't anticipate that any additional ventilation methods will be
required. A metal box (with louvers, for example) should be adequate,
since almost any environment has naturally occurring air currents.

With the module factory installed on a heatsink, mounted completely
within an unvented enclosure, the enclosure's surface area isn't
effectively coupled to the module's heatsink.
This type of installation should have some type of cooling fan or
cooling air movement added to the enclosure.

WB
...............

~Roy~ wrote:
I lucked up and found a source for KB Electronic DC controllers
locally that will sell to me wholesale. I had been going to buy one
controller in particular, that was already in an enclosure, but he
explained to me that I would be ahead in the long run buying another
model with the factory installed heatsink etc already on it, as it was
better than the ones yu could add a heat sink to as the components in
the chassis type had the items needing cooling already attached to the
heat sink, instead of just placing a heat sink against the enclosure
box itself.

So I bought the chassis type, but need to make a box for it. I plan on
making the box out of acrylic plastic, with the back of the box cutout
to allow heat sink to extend throuh outside of the box for cooling. Do
you think it would be a good idea to add perhaps a 1 1/2" muffin fan
or even a 3" muffin type fan to this acrylic box to pull air over the
internals that the box is now enclosing and duct it oput down and over
the heat sink? Or should I be able to just enclose the chassis and
have the heat sink exposed to ambient air for cooling? I do need to
enclose it as its going to be mounted in the lower section of my 20"
bandsaws base cabinet, which does get dust etc in it. I plan on
relocating the speed pot to the front of the saw for easy access just
like my old controller had..... HOw much space should I leave around
the chassis for air flow etc? I am driving a 1.5hp 107VAC 15 amp DC
motor.

Any suggestions appreciated.