View Full Version : speed controler

03-11-2010, 12:16 PM
hi guys i have a KBelectronics speed controler KBLC-240D
not sure what horsepower resister to use with my motor

kbelectronics told me to use .18 ohm but i dont think thats correct as the resistor exploded
as soon as i turn on the power LOL qwickest 10 i have spent in a while

motor specs sherline mill motor

Duty rating: Continuous--10 oz. in. at 6100 rpm, .85 amperes; Intermittent--30 oz. in. at 5500 rpm, 1.75 amperes (5 minutes on / 15 minutes off)

Output horsepower: .06 KW (60 W) at 10 oz. in. / 6100 rpm

DC voltage:90 VDC to motor (60 Hz)
Speed in rpm: 6100 rpm continuous
Class of insulation: Class A, 105 (C.) insulation system
Normal full load current: .85 amperes Starting current: 17 amperes instantaneous starting current (<100 milliamperes). This is also stall current in True RMS

anyone got any ideas???

03-11-2010, 03:31 PM
Are you sure everything is wired correctly?
I wouldn't expect the resistor to fail like that, as all it does is control how much current goes to the motor. All I'd think the wrong resistor would do, would be either not let enough current reach the motor, or too much current.
I'd try contacting KB and see what they suggest.

What voltage are you powering the KBLC with?
For a 90V motor, it needs to be powered with 115Vac...

Also, on a side note, where did you get your KB drive?
(I'm currently looking for a DC motor controller, without the expense of shipping one from across the pond)

03-11-2010, 03:51 PM
Just to clarify, what drive do you have?
Although the KBLC-240D can be found via the search on the site, it points to the KBIC manual/datasheet...

03-11-2010, 04:07 PM
the controler is in my milling machine but axiscontrols sell them here in the uk KB recon it would control my 90v motor
not sure what its getting powered buy but if you turn the max speed pot down to min you get 0-90vdc turn it to max you get 0-200vdc
not sure on the other two pots torque and cant remember what the othes called i know its some sort of compensator
i think torque is amps not sure on that though cant test what amps I`m getting

speedcontrolers hate me lol my sherline mill speedcontroler died now possably this one in my other mill all KB Controlers

03-11-2010, 04:12 PM
i have KBLC-240D

03-11-2010, 04:30 PM
should i have continuity across motor + motor - coz i have ? dont think thats right

03-11-2010, 04:55 PM
Excellent, a UK supplier for the board I need!

Provided you're aware of the voltage issue, and set the board right, then that shouldn't be an issue.

I'd double check that you've got everything wired up correctly (i.e. the motor is connected to the armature terminals, and not the field terminals...)
Failing that, I'd be contacting KB to see what could cause the resistor to blow.

03-11-2010, 07:35 PM
At the max ratings of 17amps that resistor will see 52 watts, maybe its too high a resistance!


03-11-2010, 08:23 PM
thats the resistance KB recomended for my motor .18 ohms
but another company recomended .035 ohms

i have some kind of breakout board attached to this controler i seem to be getting continuity across the +/- motor connections
on the breakout board for the speed controler but if i test the motor terminals on the main speed controler board i dont get continuity
which leads me to think i have a short on the break out board

03-11-2010, 08:39 PM
ptwj's calc is correct for the starting current.
Power = Current x Voltage, and to get Voltage drop across the resistor, we use Voltage = Current x Resistance

To get Voltage over the resistor, we use Voltage = Current x Resistance, which is 17A x 0.18 = 3.06V
Power = 17A x 3.06v = 52.02W.
For running at the continuous rating, 0.85A x 0.18 = 0.153V x 0.85A = 0.13W
For running at the intermittent rating, 1.75A x 0.18 = 0.315V x 1.75A = 0.551W
For startup.......................................17A x 0.18 = 3.06V x 17A = 52.02W

However, that is the instantaneous power consumption at switch on at full power. The KBIC should slowly ramp up to the set power, to avoid any major inrush issues.

should i have continuity across motor + motor - coz i have ? dont think thats right
What do you mean across Motor + Motor?
On the board, or the motor itself?

03-11-2010, 09:13 PM
on the speed controler breakout board i have a terminal block motor + motor -
not the motor ....

motor not connected

just used meter on the -/+ terminals for the motor

04-11-2010, 10:15 AM
well removed the breakout board and hooked the speed controler up to my meter
i think the controlers dead as it is showing 115v out put no mater what you you do with the potentiometer going to see what i does without later

04-11-2010, 03:57 PM
I'd be more inclined to test it with some sort of load on it, as the circuit may need to be loaded for the regulator to work.

04-11-2010, 09:02 PM
going to look in to getting some thing better