Klöckner-Moeller motor protectors

Slightly off topic, but I need to vent and this seems like the best place.

My 1986 J&S 540 surface grinder has a small 3-phase coolant pump. The impeller section has pretty much rotted to bits, and a couple of years ago when it failed in the middle of a part, I patched it up with some epoxy and ordered a spare. The spare was sitting in it's box until a week ago, when the motor protector for the coolant pump started to pop. So I finally threw out the old pump, and replaced it with the spare.

The old pump had a Klöckner-Moeller motor overload protector rated 0.16-0.24A. The new coolant pump nameplate said 0.28A. So I thought it would be good to replace the overload protector with the next larger size, 0.24-0.40A. I found a NOS one on Ebay for 7 Euros, and last night put it in. You'd think it would take five minutes, there are only seven connections on screw-in terminals.

The protector mates from below to a relay and auxiliary switch. Here's what a spare one looks like from the side:


Instead of five minutes, it was an uncomfortable 90-minute nightmare. You can't remove the device from the DIN rail, because the removal clip is blocked by the protector on the bottom. But you also can't remove the protector from the assembly without unwiring a lot of the device, because access is blocked by all of the wiring.







Is there anyone out there who thinks this sort of construction is a good idea? It's very hard to maintain/replace. I can't imagine a sensible engineer coming up with this. Perhaps the people in marketing - since with the space and wiring constraints it's impossible to swap this for other parts, unless you are prepared to rewire the entire control cabinet.

ballen said:

Slightly off topic, but I need to vent and this seems like the best place.

My 1986 J&S 540 surface grinder has a small 3-phase coolant pump. The impeller section has pretty much rotted to bits, and a couple of years ago when it failed in the middle of a part, I patched it up with some epoxy and ordered a spare. The spare was sitting in it's box until a week ago, when the motor protector for the coolant pump started to pop. So I finally threw out the old pump, and replaced it with the spare.

The old pump had a Klöckner-Moeller motor overload protector rated 0.16-0.24A. The new coolant pump nameplate said 0.28A. So I thought it would be good to replace the overload protector with the next larger size, 0.24-0.40A. I found a NOS one on Ebay for 7 Euros, and last night put it in. You'd think it would take five minutes, there are only seven connections on screw-in terminals.

The protector mates from below to a relay and auxiliary switch. Here's what a spare one looks like from the side:

Instead of five minutes, it was an uncomfortable 90-minute nightmare. You can't remove the device from the DIN rail, because the removal clip is blocked by the protector on the bottom. But you also can't remove the protector from the assembly without unwiring a lot of the device, because access is blocked by all of the wiring.

Is there anyone out there who thinks this sort of construction is a good idea? It's very hard to maintain/replace. I can't imagine a sensible engineer coming up with this. Perhaps the people in marketing - since with the space and wiring constraints it's impossible to swap this for other parts, unless you are prepared to rewire the entire control cabinet.

Click to expand...

Sensible engineer.....Now there's an oxymoron!!!

They DO exist.

BUT... All the DIN rail stuff I have worked with has a simple screw clamp, or even a spring clamp, to hold it on the rail, accessible from the top.. Are you saying that your device is attached in a different way?

or are you saying that the add-on is attached in a way that obstructs the clamp (I think so). If the latter, then the protector is attached later (or you could not use the clamp to attach the relay), and the removal should be possible without taking everything off.

Removing the wires will be done anyway, since you are replacing the protector, so why is removing wires a big problem?

You got a NOS part for 7 euros, that probably cost 100+ new, but your complaining because it took 90 minutes to install

You've conveniently given us no pictures of the actual mounting parts.

Generally those can be removed from the rail just by compressing a spring; you don't need to actually get a screwdriver in.

dalmatiangirl61 said:

You got a NOS part for 7 euros, that probably cost 100+ new, but your complaining because it took 90 minutes to install

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Yup, nothing informative nor asking a question, just "venting"

OP should get a month off to sit on his hands, thinking about what he did.

I have been struggling with a contactor made by the same idiots. One of the coil terminals hangs out over a mounting tab. They must have intended to use a screw with a nut, but this one in threaded into the cabinet so you can't get it out any other way except with a screwdriver at an angle.

A rotary switch by the same people has mounting holes that only allow it to be installed one way. The knob has a sort of plastic collet that is splined so it only can be installed in one position. I guess this is a German case of ordnung

I just did an inventory of my stock.
GE, AB, Eaton, Furnas and Siemens are all bottom mount with plastic latches.
You MUST operate the plastic latch with the O/L removed to have a clear shot at operating the latch by prying with a fairly wide screwdriver, and NOT by twisting with a narrower screwdriver. And NO you cannot lift the starter to clear the top fingers to get off the DIN rail.
Once you break the latch by twisting the screwdriver, you need to slide the wounded device off the end of the DIN rail, this usually requires stripping everything else off the rail and taking it out.
Occasionally I have needed to remove the lower wire way mounting screws to get enough clearance to get the O/L's off the starter.

If the OP had removed the wires one at a time from the O/L and labeled them after pulling the wire into the wire way it probably would have been a half hour to 45 Min job depending the box location.

Since this was the OP's first rodeo with these crappy starters, and he really got'er done in an hour and a half and it appears to have worked when done. He did a real good job. (Pat, Pat on the back).

Many call for help after it is mostly apart with a broken latch or two and none of the wires are labeled, and Oh no schematics to boot. Oh what fun!

It is real fun when the bottom of the box is only 3" from the floor.

I will be 71 next month (50 was 21 years ago and much, much less mobility now) and I have had my fill with these crappy starters and overloads. I will be working on a grinder with 2 of them in a few days, It is really a fun shop to work in. I have retired from the ones where they rip things apart and have a real mess to fix.


Bill

Replying to the comments:

JST: you can remove these from the DIN rail by pulling directly down on a white plastic clip which retracts the retaining finger from the rail. BUT that white plastic clip (with a convenient screwdriver slot) is only reachable AFTER you have removed the motor protector, which totally blocks access! Point is you need to remove many wires unrelated to the motor protector to get it off. Maybe not a problem if the control box is lying on a workbench next to you. But when the assembly is mounted vertically 250mm from the ground and buried in a box, it's quite a hassle.


dalmatiangirl61: yeah, I'm complaining about the mechanical design, which makes it hard to maintain and/or swap

SomeoneSomewhere: photos are in my first post. Spring is compressed to install, stretched to remove. No way to do that without disassembling the "daughter" components first, and hard to get those off until device is removed from the rail. Catch22.

9100: I feel your pain. Happy that someone here "gets it"!


Bill: yup, exactly, you get it too. And thanks for the kudoes. Yes, it worked correctly the first time. Fortunately one of the early wires slipped free after I "tightened" it, which got me to study how the wire clamps operated and work accordingly. This one was 10" off the floor, where the only way to work was balancing on my 60+ year old knees while holding the needle nose pliers in one hand, the screwdriver in the second hand, the flashlight in the third hand, and the magnifying glass in the fourth. If the box was horizontal on a table in front of me with good lighting and seating I would have had it done in 10 minutes. Which is probably what the engineers had in mind. And yeah, the wireway is just below the switching, with wires that have no free play. It's not the first time I have done this, but in the past there was a bit more room. So I did make careful notes, made easier because the wires are all numbered already, disconnected the dozen wires, got er off, swapped, and back on. But at the end of the day I really wish the designers had just found a more user-friendly way.

PS: of course you can't just make a table of the wiring first, because it's so inaccessible that the only way to identify the wire numbers is AFTER they come off and after you have pulled it partway out of the wireway.

I woorked for K-M for 6 years, I can attest to the fact that EVERY detail of the assembly was thoroughly "rationalized" (their wording) for simplicity, repeatability and durability, within the design parameters of what IEC components are used for.

Three screws to loosen on the OL relay to pull it off of the contactor and move it to one side, hanging off of the motor leads. It's done this way on purpose because 99% of the time,you have to replace only the contactor, not the OL relay, so you don't have to remove your motor leads. The DIN rail clip is NOT supposed to be twisted to activate it, that's why it is breaking. You use a long shaft screwdriver into the slot and leverage it against the contactor body, pulling it straight out toward the bottom to unlock it from the bottom of the DIN rail**. Then you tilt the contactor back and lift it off. The entire operation should take less than a minute to remove, the same to reinstall. The new one came with a pictogram instruction sheet showing each step.

The big problem with this stuff is that in other parts of the world, ALL similar equipment is designed basically the same, so when a technician goes to trade school, they are taught how to do it. But over here, people just sell them, expecting others to figure it out on their own. When I worked for K-M, we put on one-day training seminars for our customers to show them how to deal with IEC designed components. Now that K-M has been gobbled up by Eaton and made to be part of Cutler Hammer, they just defaulted back to "let 'em figure it out" mode.

** One of the problems that happens here in North America is that OEMS buy DIN rail from the cheapest source they can find, and not all DIN rail is created equal. There are several "thicknesses" of the metal material, based on the expected use and weight of the devices to be mounted. These have very specific DIN numbers assigned to them and the instructions for the device will reference the exact DIN number of rail that is to be used. But here, people are not trained on that, so they just buy one rail and use it for everything. What ends up happening though is that the thicker rail will not easily release the devices designed for thinner stuff. Thicker STEEL rail would disallow it to be mounted in the first place and give you a clue as to having the wrong version, but because people want to be able to cut it easier, they buy aluminum thicker rail and force it on. Then the steel mounting clips on the devices dig into the aluminum over time and vibration, making it difficult to remove the devices later. That's not a design issue, that's an ignorance issue.

9100 said:

I have been struggling with a contactor made by the same idiots. One of the coil terminals hangs out over a mounting tab. They must have intended to use a screw with a nut, but this one in threaded into the cabinet so you can't get it out any other way except with a screwdriver at an angle.

Click to expand...

All IEC devices are made to mount on DIN rail only. The "mounting feet" were an afterthought for Americans who insisted on it.

A rotary switch by the same people has mounting holes that only allow it to be installed one way. The knob has a sort of plastic collet that is splined so it only can be installed in one position. I guess this is a German case of ordnung

Click to expand...

The rotary switches are designed to have a nameplate installed in their face, showing the switch positions. Why would you want a handle that can be misaligned so as to not line up to those designations?

jraef, the power distribution stuff in my house and workshop uses DIN rails and IEC devices. It takes me a few easy minutes to swap a 3-phase circuit breaker there, and it works well. Why? There are typically three connections below the device going to the load, and three above bringing power in (and perhaps out). These are accessible with the device mounted. If I want to unmount it, the release tab is visible and accessible with the wiring in place. The multiple rows of DIN rails are spaced far enough apart so that access to the wires above/below is easy. The box is mounted (probably a code requirement) around eye level. The wiring is all at a single level, on all of the devices.

The control cabinet on the J&S540 is a stark contrast to this. In part, this might be because the machine (d)evolved from the first 1940s versions in which the controls (cross/down feed) were purely mechanical, and the only electrical parts were power going to a 3 phase spindle motor and a 3 phase coolant motor. By the time my machine (J&S 540APR, production year 1986) was produced, the controls cabinet had grown to this 75 x 100 cm (30 x 40 inch) monstrosity, which is almost as big as the original machine base.



Note that it's mounted at floor level. Here's what it looks like inside:



My issue is with that upper row of K-M components, especially on the left side, and those in the bottom left corner. Those layers of wiring on different levels, combined with the inability to remove the device, the lack of space on either side, the floor-level mounting, and the lack of any slack in the wiring, conspire to make maintenance of those K-M devices a nightmare. The front panel switches and knobs are also problematic, it's almost impossible to test/remove/swap one of them without removing most of them.

By the way, the DIN rail is the correct one for these devices: once you have removed a dozen wires and the OL to access the tab, it attaches and removes easily enough.

About the only good thing I can say about this design is that I do have a full set of original schematics and the corresponding mechanical drawings, so when something goes wrong I can at least locate the suspect devices. But to test/remove/swap them is awful. Bill knows exactly what I am talking about!

Probably, with decent access, it would not be so bad.

That does look very tight, and the bottom level looks as if you must stand on your head to see it. I do not like such arrangements, they seem to have been invented to take the least space, rather than having any concern whatever for maintenance.

The wireways are also an issue. I suspect they are in no way full of wires, so no reason to be that tall, it just obstructs access even more.

JST said:

The wireways are also an issue. I suspect they are in no way full of wires.

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Yup, standing on your head is needed for the bottom row. Also helps if your eyes are at the top of the head, not in the normal position.

Unfortunately the wireway below the long row of K-M devices is absolutely crammed with solid-core wires. It's hard work to get a wire out, even if one end is free.

Jraef said:

The rotary switches are designed to have a nameplate installed in their face, showing the switch positions. Why would you want a handle that can be misaligned so as to not line up to those designations?

Click to expand...

The nameplate is removable, necessary to remove the screws under it, and it can be replaced in 4 different positions. In this case, I wanted to reorient the switch to make leads more accessible. Because the knob only fits one way, off and on will be in funny positions. Not really a great hardship, but still poor design.

Bill