Author Topic: KD250 fan switch issues (Read 781 times)

Southside · « **on:** October 10, 2018, 11:20:06 AM »

Ok - so I am going to have to work here to keep this from becoming a rant as I really would like some ideas, but for several reasons I am frustrated.

My WoodMizer KD 250 is installed in an insulated shipping container with 6 fans in the overhead truss. Fans are wired for 240V A/C using three home runs of #12 THWN between each fan and thermal overload switch. (one wire for each leg and one for the ground). So each fan has it's own conduit in which three wires run. Ground legs go to a buss bar, which is then connected to a driven earth rod via #4 bare copper wire at the bottom of the controller box, maybe a 7' run of copper. The same buss is additionally connected to the sub panel ground via the UF feed line. The neutral and ground in the sub are not bonded, but they are in the primary disconnect that first feeds the whole system.

Power to the whole kiln comes from a 200 amp sub panel which has a dedicated 50 amp breaker and is connected via #6 UF resulting in 240VAC at the point of distribution, and on the input side of the switches - checked via multi meter.

The switches are flush mounted to the face of a NEMA enclosure which serves as a wire keeper for all of the non probe wires which enter the kiln. Probe wires go through their own conduit into the chamber to eliminate any potential RF issues. All electrical wire is in CPVC conduit from the box to the motor itself. The kiln controller and NEMA switch box are then located inside of a "dog box", complete with roof, which is attached to the side of the shipping container.

When I first ordered the 4 additional fans for my kiln one of the overload switches would not close and start the fan motor, my switches are numbered 1 - 6 for each corresponding fan and I don't recall which one it was. I checked all the connections, voltage, free spin of the motor at the time and finally swapped out two of the switches to try and determine if it was a switch or motor issue. The motor which would not start initially now started and ran fine with the alternative switch in place and the motor which had been running would not start with the suspect switch in it's place. So - bad switch from the factory - stuff happens.

I called the ASC I had purchased the kiln through and they told me to call Nyle directly, which I did, and they sent me a switch. Fast forward a month or so and suddenly a second switch - in a different position - would not hold closed. This time I called WM in Indy directly and they sent me a switch. By this time I am getting tired of opening up the NEMA box to replace switches, but figured again - things happen.

So last week yet again another switch, in a different motor position, won't stay closed. I call Indy and spoke with the parts folks and got a bit of a run around when explaining the problem, questions about voltage drop, wire run length - I always oversize wire - the switch trips out at 3.5 amp and I have each circuit on 20 amp wire - eventually they agree to send me a switch. I was a bit put off by the conversation seeing as how I have been in contact with Indy almost daily the past week about buying a 4000 they had coming in used or a Super 70, they have been the ones who needed to get additional info on the deal.

Yesterday I fill the kiln and go to turn on the fans to move some air while hooking up the probes and tarps, only having 5 working fans as the replacement switch has not made it yet, when the #2 switch trips out on me, so I try again and it stays closed, I thought sure enough - it's about to go. Shut it off and I check for free fan spin, open the box, check input voltage - 240VAC, connections are tight.(breaker was off and on during this process) So I put it all back in and try it - yup - she is dead, won't start the fan. Once again I take another switch that is turning the fan and swap the two out - motor starts and runs fine and the the motor with the #2 switch won't start.

So at this point I am convinced that I have a bad batch of switches that Nyle orders from a mfg in Mexico and Wood Mizer sells to me under their brand, it's 4 out of 6, all in different motor positions, one being bad the day it arrived and the others dropping off randomly. There is zero water intrusion into the dog box, liquid tight connections at the motor pecker heads, and absolutely nothing in the NEMA box, no issues with the actual kiln controller and no issues with anything else that is on that same sub panel.

I figured I would call Indy and ask to speak with someone higher up the chain and ask for a new batch of switches as my confidence in these is just not there, yes some are new, but I did't record which are which and I offer to send back - at my expense - the old switches. The response I got was actually that WM feels I have a something wired wrong as nobody else has any problems - I happen to know for a fact that not everyone uses these thermal overload switches rather they wire to a breaker directly. We go over wire sizes, ground rod, voltage drop, etc - yup I must have something wired wrong is the WM consensus, can't tell me what, but I have something wrong that causes an intermittent issue on a different circuit each time. I was told that the switch manufacturer will claim they just don't have quality control issues, so I again offer to send back the old switches, the response is that it won't help to determine if the switch is bad or not. Eventually I was told a new switch would be sent to me, and I was given a name to send back the bad switches to - at my expense - but honestly is this the new way in which warranty issues will be handled? I am not trying to build a free kiln one part at a time, rather I would like my rather expensive piece of semi-autonomous equipment to sit there and work the way it is designed to so my lumber dries properly and I can focus on running the parts of my business that require my attention and input.

Again - really not trying to turn this into a rant, and obviously from my other posts and present pending purchase of a mill that cost more than my first house, I have been happy with WM products. So - and I realize it's hard to ascertain without being able to see it directly, but does anyone see a problem with how I have my kiln fans / over load switches wired in? Any suggestions or trouble shooting ideas that might help to figure out what the issue is?

Thanks

Jim

YellowHammer · « **Reply #1 on:** October 10, 2018, 01:48:38 PM »

As you say, I didn't install the switches for my unit, if they were like the ones I received, they looked very unsuited to the situation to me. One look, and I threw them into the garbage can.

If I was going to wire in the fans individially, I would use a Square D style panel breaker box, with a 3.5 amp or 5 amp whatever suitable breaker that they have for each fan. Much more robust system, much more reliable with proper grounds and safeties. I use this system to turn on all the fans in my unit, and it has worked fine for years.

GeneWengert-WoodDoc · « **Reply #2 on:** October 10, 2018, 05:18:39 PM »

I would think that for $100 you could have a licensed commercial electrician visit and identify the problem. If it is Nyle’s issue, I would ask them to forward $100 as well as parts.

What concerns me most in your saga is that the switches become inoperable without any signs of heat damage.

Southside · « **Reply #3 on:** October 10, 2018, 09:02:58 PM »

Gene in reply to your comment about the visible heat damage I have seen no indication of heat along the wire insulation or the case of the switch. All wires leaving the switch and going to the fans are a single non spliced run, so no connection point to generate heat and resistance. That being said you reminded me that I have an IR thermometer that I keep of all places right in the dog box as I use it to check actual lumber temp when setting pitch. So just an hour ago I did a little temperature recording. The kiln has been on for about 36 hours this run so far. The results are below:

Gallon of distilled water kept in the dog box for use in the wet bulb reservoir: 86.9F
Hottest point of the hottest switch 93.7F - all the others were within 1 or 2 deg
KD 250 main power switch 93.9F
KD 250 display hottest point 99.3F

Thank you for the input.

YellowHammer · « **Reply #4 on:** October 10, 2018, 09:45:57 PM »

I'd pull the switches apart and identify the failure scenario, which should be repeatable since you have a significant set of failed switches. If nothing else out of curiosity.

Southside · « **Reply #5 on:** October 10, 2018, 10:42:32 PM »

I tossed the older ones, but I do plan to pull these apart before sending them to WM, I will take photos.

K-Guy · « **Reply #6 on:** October 11, 2018, 10:59:45 AM »

Hi Southside Logger
Stan from Nyle here. We've used those switches for years with no problems to speak of. It sounds like you are doing everything right but there has to be a problem. So far you are the only one with these problems and I wonder if another set of eyes might find the problem. If you think I can help feel free to call.

Southside · « **Reply #7 on:** October 11, 2018, 02:58:14 PM »

With all due respect Stan, if you read my post you will see one was faulty upon arrival. I guess I should have pulled apart one of the earlier ones that were bad.

I am open to anyone coming and looking at the unit.

K-Guy · « **Reply #8 on:** October 12, 2018, 08:56:14 AM »

Southside Logger

I apologize if I offended you but we've had such good performance from these switches and you have been the only one with this problem so far.

I'm starting to wonder if the motor might be the culprit. It could be drawing just heavy enough to put a strain on the overload in the switch without tripping it and that is causing premature failure of the switch. I can't say this for sure but if it is the same fan all the time, it could be. I'll contact Wood-mizer and discuss it with them.

K-Guy · « **Reply #9 on:** October 12, 2018, 09:11:52 AM »

Southside Logger
I spoke to Mike at Wood-mizer and he'd like to help you. You can reach him at 800-525-8100 ext 1601.

Or you can call me at 800-777-6953 ext 212 and I'll try to help you.

Southside · « **Reply #10 on:** October 12, 2018, 09:21:37 AM »

Stan,
No offense taken, but my point is that it is not the same motor that has encountered a switch failure each time. One came non functional, and as I said things happen, Nyle replaced it, but one by one the others keep dropping off randomly. The 3rd one worked when I shut the kiln down, went to fire it back up and it would not stay closed. There is no pattern to it. I would completely agree that if it were on the same circuit each time there would be a common problem in either wiring or a motor / physical issue, but that is not the case.

I will give both of you a call later on today.

Thanks you.

scsmith42 · « **Reply #11 on:** October 13, 2018, 09:48:13 PM »

Actually, I’ve had problem with my switches too (going back several years). I’m using an L/200 WM400 in a container kiln that I built in 2003. It has six fans that were all sourced from Nyle (Grainger units). Over the years I’ve probably replaced 3 of the 6 fan motors.

So far, I’ve replaced 3 of the 6 Nyle switches with standard 240VAC light switches. No issues with the light switches.

I’ve found that when the capacitors start to get weak the switch breakers will trip. When the switch breakers trip sometimes if I try to start the fan several times in a row the switch will finally stay on.

Other times if I have someone get the fan spinning before I flip the switch, it will stay on.

But the long terms solution for me has been to eliminate the circuit breaker switch that came with the units.

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