Kay Rotary Phase Converter not starting. Help?

[Phillip Mitchell]

Yesterday I went to start my 10 hp Kay RPC and twisting the on / off switch resulted in nothing. Almost like there was no line power going to it, but there is.

I’d used it a few hours earlier with no apparent issues and have had it since 2020, replaced all 8 caps (start and run) with new from Kay nearly 2 years ago. I think it was manufactured in 2005 according to serial # from Kay Industries.

I have not yet tested the caps this time.

According to my multimeter, there is power ~250v coming into the the on/off switch. Turning switch to On results in nothing happening and no power on the downstream side of the switch.

The line power coming into the RPC is on a dedicated 60 amp 240v breaker and 4 gauge wire. The breaker was not tripped but I cycled it off and on (a couple of times) and attempting to start during my initial troubleshooting.

I will be calling Kay on Monday AM and talking to their tech support, which has always been very generous with helping me in the past despite me buying the unit used and being long past any sort of warranty on my older unit.

Any thoughts or starting places for trouble shooting that I may be able to narrow down before talking to tech support on Monday?

I have already been on the Phase Perfect website looking at the enterprise line of 10 and 15 hp units as well as American Rotary 25 hp digital units…I use my shop everyday professionally and have every major power tool except bandsaw, jointer and dust collector depending on my RPC setup so downtime is a major concern and do not have the luxury of a relaxed troubleshooting and repair process.

Thanks for any help.

[Paul F Franklin]

If I read this right, you have 240 volts at the input of the switch, but 0 volts on the output terminals of the switch, when the switch is in the on position. That says it's probably a switch problem. I'd check the connections to the switch and if they're all tight it's probably the switch. You could kill the breaker and temporarily jumper out the switch and then use the breaker to turn it on and off until you can replace the switch.

[Bill Dufour]

Is it a mechanical switch or does it control a contactor? I agree the switch is bad. Does it have overloads?
Bill D

[Phillip Mitchell]

Bill,

This is the existing switch (photo 1 in my post)

https://www.galco.com/ot80ft3-abbg.html

It looks like it does go through some fuses and traces over to this contactor downstream of the switch

https://www.se.com/us/en/product/8910DPA33V02/contactor-definite-purpose-30a-3-pole-20-hp-at-575-vac-3-phase-110-120-vac-50-60-hz-coil-open/

I do not see overloads anywhere in the control box but am not an electrician or engineer so… the last photo in the OP shows the entire box. The caps are in another enclosed area on top of the idler motor.

I went ahead and ordered a new switch online because (down)time is of the essence. I have a 60 day feee return window if for some reason it’s something else.

[Bill Dufour]

Turn the switch on. Push in that dark square on the contactor face with a piece of dry wood. That should close the contactor. Try a few times with power off first to get the feel.

It does look like that switch switches full amperage. I would call it a disconnect only used after the contactor is open.
Bill D

[Bradley Gray]

I have the same converter without the built in switch fed through a service disconnect with 2 60 amp slow blow fuses. The schematic from Kay shows it wired this way so the model including a switch likely has some fusing.

[William Hodge]

Turn the switch on. Push in that dark square on the contactor face with a piece of dry wood. That should close the contactor. Try a few times with power off first to get the feel.

It does look like that switch switches full amperage. I would call it a disconnect only used after the contactor is open.
Bill D

Touching live stuff with a piece of wood isn't OK. Think about wet wood triggering a Saw Stop.
If you go to reach for the wood, grab a phone instead and call an electrician instead.

[Phillip Mitchell]

My contactor does not actually have a live switch to press.

It seems like I have isolated the issue to a bad fuse, which I suppose, happens from time to time on older electrical components. I have a few pairs on the way for replacement and backup as well as a replacement switch that I may just keep on hand for backup.

If I have learned anything here it is that the down time can be a killer and major stressor. Thankfully, *fingers crossed* this was a relatively quick and cheap fix, but I am still looking at Phase Perfect as a potential replacement for a few reasons, and will continue to add to my stock of emergency replacement parts to keep downtime to a minimum in the interim.

[Robert Hayward]

Touching live stuff with a piece of wood isn't OK.
Please take note of the wording Bill used. His statement says dry wood.

[John Lanciani]

Touching live stuff with a piece of wood isn't OK. Think about wet wood triggering a Saw Stop.
If you go to reach for the wood, grab a phone instead and call an electrician instead.

Before fiberglass, linemen's hot sticks were made of wood. From Wikipedia;

"Early hot sticks were made from wood and need to be lightweight to prevent fatigue on linemen. Sitka spruce is the most popular wood used in the construction of hot sticks due to its light weight, strength, and excellent electrical properties. Hot sticks are now generally made from high strength plastics with an aluminum alloy head. This makes for an even lighter hot stick. "Insulation characteristics and strength of the tools are of major importance, as the linemen's safety depends upon these things. The ease with which the tool handles, the relief from fatigue, the manner in which it operates when engaging a tie wire, strain clamp insulator, or conductor are also important considerations."

Personally, I just use a Klein screwdriver to push in contactors for testing.

[Bill Dufour]

Railroad signal boxes use wooden boards to mount and insulate the electrical terminals. Later they switched to Bakelite when it got invented. I am sure some are still in use with wooden insulator boards.
We are only talking 240 volts. One piece of electrical tape is rated at 600 volts. Clean dry wood, no paint,varnish or staples. At least one foot long so you hand stays well clear of the interior of the box. Wear real shoes or boots. not flip flops, dry floor etc. One hand in pocket if that makes you feel safer.
You admit sawstops sends no measurable voltage through dry wood.
You do know never to paint your ladder don't you?
Bill D.

[Jason Roehl]

Personally, I just use a Klein screwdriver to push in contactors for testing.

I test about 18 contactors per week using either a plastic-handled screwdriver, or a plastic retractable ball-point pen. This is to test-run the fans on two 170-ton 480V chillers. The fans are 480V, 3-phase as well. Just have to be careful where you’re poking that screwdriver.