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Hukshawn
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Anyone know these fairly well? I have questions about the current limiting.
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I'm somewhat familiar, ask away
Mark
Mark
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Hukshawn
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Ok. I'll try to paint a good picture.
So, it's a 90v 2.5 hp DC motor
The 1hp current limiting (horsepower) resistor is installed, I have a 1k pot.
The motor ran fine under no load fine previously, got it hooked up to the lathe, seem to run fine, but it seems to be getting weaker the more I try it. The current limit led glows and it runs pretty slow. I've read all the manual and have tried adjusting the trim pots. I can get the motor to run better but I have to crank the current limit pot up pretty high.
No way the motor has to push 150% of 1HP to just run the lathe under no load.
And now if I take the belt off the motor, the motor hunts for the speed it's set for. I can adjust that with the IR trim pot, but again, seems to be much higher than recommended.
And the resistors get hot.
What have I done wrong? I have checked all my connections and nothing seems to be grounding out. I know some of my items are not as they should be, the speed pot, the resistor, but they shouldn't make THAT big of a difference. And the worsening performance bothers me...
So, it's a 90v 2.5 hp DC motor
The 1hp current limiting (horsepower) resistor is installed, I have a 1k pot.
The motor ran fine under no load fine previously, got it hooked up to the lathe, seem to run fine, but it seems to be getting weaker the more I try it. The current limit led glows and it runs pretty slow. I've read all the manual and have tried adjusting the trim pots. I can get the motor to run better but I have to crank the current limit pot up pretty high.
No way the motor has to push 150% of 1HP to just run the lathe under no load.
And now if I take the belt off the motor, the motor hunts for the speed it's set for. I can adjust that with the IR trim pot, but again, seems to be much higher than recommended.
And the resistors get hot.
What have I done wrong? I have checked all my connections and nothing seems to be grounding out. I know some of my items are not as they should be, the speed pot, the resistor, but they shouldn't make THAT big of a difference. And the worsening performance bothers me...
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Hukshawn
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Further...
Since I am running a 2.5 hp motor, what's the risk of just by passing the limiting resistor? Would the board not just push its maximum current?
I replaced a 1 hp motor on this lathe, so even 1.5 is more than I had. I've never stalled the old motor.
I just ran the lathe with a piece of wire by passing the plug in resistor and it ran great. The current limit led didn't glow, I was able to turn the current limit trim pot wayyy down as well as the IR trim pot...
Since I am running a 2.5 hp motor, what's the risk of just by passing the limiting resistor? Would the board not just push its maximum current?
I replaced a 1 hp motor on this lathe, so even 1.5 is more than I had. I've never stalled the old motor.
I just ran the lathe with a piece of wire by passing the plug in resistor and it ran great. The current limit led didn't glow, I was able to turn the current limit trim pot wayyy down as well as the IR trim pot...
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Hukshawn
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How hot do these boards generally get?
I realise it's the mosfets that should be hot... But there is a large resistor that gets quite warm and the DC output fuse (which is under rated till the ones I ordered come in next week) is getting quite warm.
Should I install a fan on this?
I realise I'm throwing a bunch of crap out here, but I'm not familiar with these DC drives and I'm flying blind.
I realise it's the mosfets that should be hot... But there is a large resistor that gets quite warm and the DC output fuse (which is under rated till the ones I ordered come in next week) is getting quite warm.
Should I install a fan on this?
I realise I'm throwing a bunch of crap out here, but I'm not familiar with these DC drives and I'm flying blind.
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Ok it sounds like your horsepower resistor needs to be a smaller ohm value. You probably were on the right track when you just used a wire in place
of the resistor. What you could do is make a small coil of wire say about 4 or 5 inches of # 20 gauge wire wrapped around a plastic rod. That might get you closer. Experiment; try a couple different ones. Ideally you want to be about halfway on the IR pot. If the motor speed drops under load you turn the IR pot clockwise I believe. With your 1 hp resistor you're getting too much current feedback so the controller is throttling down the output power.
I wasn't sure if your motor was really rated for 2.5 hp since the treadmills are often way overrated.
There is a large resistor probably green blue red that will get pretty warm. The HP resistor should not get very hot. The SCRs screwed on the back will get warm.
You should mount the controller on a piece of aluminum as an extra heatsink and/or have a small fan for cooling.
Mark
of the resistor. What you could do is make a small coil of wire say about 4 or 5 inches of # 20 gauge wire wrapped around a plastic rod. That might get you closer. Experiment; try a couple different ones. Ideally you want to be about halfway on the IR pot. If the motor speed drops under load you turn the IR pot clockwise I believe. With your 1 hp resistor you're getting too much current feedback so the controller is throttling down the output power.
I wasn't sure if your motor was really rated for 2.5 hp since the treadmills are often way overrated.
There is a large resistor probably green blue red that will get pretty warm. The HP resistor should not get very hot. The SCRs screwed on the back will get warm.
You should mount the controller on a piece of aluminum as an extra heatsink and/or have a small fan for cooling.
Mark
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Hukshawn
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Ok super. Thanks for replying.
You're suggesting basically making a choke in place of the resistor. I can do that.
Yes, the other large resistor gets hot.
The board is mounted on a very large heatsink already that I have screwed inside the metal box, but I have a fan I was planning on using. I will connect that.
Yes, I doubt the motor is 2.5 HP but I assume it will be more than 1.5, which is the max this board will push.
I'm glad you didn't mention anything about risking burning the board out. You obviously don't think that's an issue.
I feel better now.
You're suggesting basically making a choke in place of the resistor. I can do that.
Yes, the other large resistor gets hot.
The board is mounted on a very large heatsink already that I have screwed inside the metal box, but I have a fan I was planning on using. I will connect that.
Yes, I doubt the motor is 2.5 HP but I assume it will be more than 1.5, which is the max this board will push.
I'm glad you didn't mention anything about risking burning the board out. You obviously don't think that's an issue.
I feel better now.
Hi Shawn
+1 to Mark's comments.
I would add: because these drives are intended for multi drive installations like conveyors and process lines, their range is by design limited. I used them extensively in the outfeed of newspaper presses. They are an excellent product.
I would replace the CL resistor with the max value recommended for the drive and if it does not perform to your needs, the drive is just to small for your motor.
+1 to Mark's comments.
I would add: because these drives are intended for multi drive installations like conveyors and process lines, their range is by design limited. I used them extensively in the outfeed of newspaper presses. They are an excellent product.
I would replace the CL resistor with the max value recommended for the drive and if it does not perform to your needs, the drive is just to small for your motor.
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Hukshawn
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The only issue I’m having with the resistors... is getting them.
They are difficult to find available to Canada. eBay has a few, not bad at $3 but the $35 shipping (close to $50 by the time is it’s Canadian) is making it difficult to justify...
They are difficult to find available to Canada. eBay has a few, not bad at $3 but the $35 shipping (close to $50 by the time is it’s Canadian) is making it difficult to justify...
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Hukshawn
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I emailed kB electronics for advise yesterday.