Magnetic switch expertise needed !
I was given a 1987 Grizzly 1021 15 ” planer by a family friend. He had purchased it in 1987 but as it required some extensive rewiring in his 100 year old house it was never run since leaving the factory until the other day. It runs for 3-5 minutes and then the magnetic switch trips (sometimes it makes a fairly loud sound when it does). It takes a minute or two to get to where the stop (reset button)allows it to restart but it cuts out again soon. The motor does not feel any hotter than my jointers does after the same time span. I opened the switch cover and noticed that it appeared that it was possible to adjust the switch. Of course this should have been done at the factory but I am wondering if it could be the problem. What really leads me to think that is that there is dial that has markings on it from 3 o’clock to nine o’clock. At three o’clock is just a line (-), next (clockwise) a 10, then two more lines, then a 12 (at the 6 o’clock position) then 2 more lines, then a 14 and finally a line at 9 o’clock. The indicator is pointing at the line just before the 12. On the outside of the switch is a plate stating that the switch is rated for 220 volts, 12 amps. The motor plate states the same. Perhaps you can see what I am getting at :should the indicator point to 12 instead of the (11?) it is pointing at now ? Lastly I will add that there is also a sliding switch that has the letter H on the left and the letter A on the right and the sliding swtch is all the way over at the H.
Thanks to any who can advise me!
Replies
In my opinion and experience you should be talking to the factory or better yet an electrician or your local motor repair shop. I maintain equipment such as a 12" moulder, 40 hp dust collection, saws, planers, etc. and do run across electrical issues from time to time and a woodworking forum is the last place I would go for electrical advice.
Have you looked inside the cover of the switch, often there are basic set up instructions attached there. The setting on the switch should match the amperage on the motor, you wouldn't be taking a big risk by moving the setting up one notch.
After having sat idle for so long it is possible that some part of the planer is siezed up and putting a higher than normal load on the motor, a very stiff drive belt is another possibility.
John
It sounds like it's shutting down on thermal overload. Rather than assume that the switch was set wrong by the factory I'd do the following first. Verify the wiring is no smaller than #12 and no longer than 50'. Low volatge will increase the current and cause overheating. If you have access to a clamp-on ammeter verify the voltage and running current under load. Sitting around that long the motor's cooling passages may be plugged up with spider or mouse nests or something else along those lines. I can't imagine a mechanical problem severe enough to cause overheating that wouldn't be self evident (squealling bearings, smoke, ...). I'm pretty sure the dial is for amps and should be set to match the FLA value on the motor nameplate, but I'm not sure about the H/A slider switch. It may just be for auto or hand reset of the overload relay??? The 11 amp setting vs. 12 amp setting shouldn't be enough to make the difference unless you're taking a big cut and demanding max. power out of the machine. I have a 2 hp starter I bought from Grizzly a year or so ago still in the box. I'll check the paper work that came with it tonight.
John O'Connell - JKO Handcrafted Woodworking
Life is tough. It's tougher if you're stupid - John Wayne
This is all good advice. I happen to be an electrical engineer (BSEE) and I have been working in the industrial controls field for many years. I too would start with measuring the actual current draw. A synchronous motor will try to run at a set speed based on line frequency. If the voltage is insufficient, it will draw more current in an "attempt" to keep the total power to the motor sufficient to drive the load at rated speed.
The voltage could indeed be low due to improper line-sizes or lengths.
Mike
I believe that H/A switch is exactly what you posited; I recall a while back someone with a Unisaw that was set up incorrectly out of the crate, one problem being the manual reset instead of auto, the other being too low a threshold. Those little full-voltage push-button station/starters are all pretty similar.
To ofausto: The main function of a starter, besides manual start/stop, is to provide overcurrent protection for the motor (that's why, under NEC 430 motor installation rules, you could have a 50A breaker on 12 gauge wire). Since the very essence of such a device is to control and limit current, the only way you will know anything about what it's doing (or not doing) would be to first measure the running current. Clamp-on ammeters are cheap an Radio Shack (I think around $12), and accurate enough to tell you whether it's pulling full-load current when it's idling (and supposed to be drawing a fraction of FLA).
Possible causes of overcurrent, if that's what's really happening, would include the centrifugal start switch not letting go, a bad run capacitor (if it has one), and incorrect mains voltage (running a 240V motor on 120V). The branch circuit wiring size and run, if it's 240V, will have relatively little effect on current draw, but do make sure (with a Wiggy or multimeter) that you are feeding it the correct voltage. Be seeing you...
This brings back a bit of electrical trivia I ran into a number of years ago concerning capacitors.
I had purchased a pair of new oscilloscopes that had been in storage for years, they had never been plugged in. Like motors, scopes have large capacitors and both scopes failed identically after being plugged in for about five minutes. Turns out that large liquid filled capacitors need to be "broken in", a chemical change occurs in them when they're first put into service. If new capacitors sit too long without being used, they lose the ability to break in properly and don't have the correct electrical value for the application and may also allow current to leak through them. This would explain why your motor is drawing too much current. If the machine is adequately wired, and the starting switch isn't frozen, you probably need new capacitors on the motor.
Out of curiousity, does the motor have two capacitors? The second capacitor is a run capacitor and is more likely to create the problem you describe. A single capacitor motor disconnects the capacitor within seconds of the motor's starting and wouldn't create problems after several minutes of running. Two capacitor motors leave one capacitor permanently connected and, if that capacitor were defective, it would cause the problem you're experiencing.
Hope this helps, John
I looked at my Griz starter last night, but the paper work consisted of a drawing of the starter - no instructions what-so-ever. Looking at the the labeling I'm sure the dial is for amps and should be set to match the nameplate of the motor FLA or FLC. The H-A switch on mine is M-A and it is to select manual or automatic reset of the overload relay. Let us know what you find.John O'Connell - JKO Handcrafted Woodworking
Life is tough. It's tougher if you're stupid - John Wayne
What would the capacitor(s) look like? And where would they be located? I assume in one of the two metal boxes mounted on the outside of the motor. For more , see my response to BleuBassplyr.
Since the planer sat without being used for over 15 years, I would be suspicous of the bearings and othe mechanical components. Check the current being drawn by the planer, and compare that to the numbers on the motor name plate. If it is higher, (and the overload seems to sugest it is) perhaps the planer is not running correctly. check all moving parts and make sure the run smooth.
All those folks have offered excellent advice but I would still call Grizzly before spending lots of time testing the power, etc. They were very helpful to me after I bought a tablesaw from them that had a missing latch for the motor cover. Good luck.
Thanks to all for your input . Called grizzly, they said that the setting is approximate and that you can safely adjust it upward. I did so, incrementally and now have the switch at what would be about 13. I haven't tried an long (1 hour plus) run but unless I experience trouble when I have reason to plane so much I am hoping my troubles are over. I am tempted to to get a clip on amp meter.I will stop by radio shack as suggested. I will post my readings here. It will be interesting to learn if the motor is running at over 12 amps 220 or if the switch dial is really off. JohnW's remarks about capacitors were interesting but I don't know what they look like so i can't say if it has one or two.
Keep a couple of things in mind while you're checking the performance. The current draw of the motor at full load is based on maintaining the voltage shown on the nameplate (230V if built to NEMA standards) at the motor terminals. So when the motor is producing nameplate output power, it will draw approximately the current value indicated at the voltage listed. If the voltage is lower than the nameplate value, the current draw will be higher. While you're less likely to have an undervoltage problem with 240V compared to 120V operation, it is something to check.
Another important consideration is that you never really know how much power the motor is outputting. As with table saws and other hand-fed machines, you can easily take too much of a bite and overload the motor. An induction motor will output from 1.5 to 2 times it's rated power before it stalls (or suddenly drops in speed, with the start windings engaging), so you could be overloading it somewhat and not even know it, possibly explaining it's tripping out on overcurrent.
Which leads back to needing to measure current draw while it's planing, and checking the voltage at the motor terminals at the same time. Get the Radio Shack clamp-on meter, or something like it. You'll find lots of uses for it once you have it. It comes with leads, so you can check the voltage, too.Be seeing you...
It was tripping in a no-load situation as well as under load. The time from start to trip was identical in either case. I had checked the voltage at the wall outlet too and it was 220.
1980's Grizzley stuff requires special considerations. There was often sea water corrosion inside the electrical controls. If you took it to a small motor shop, they might be able to tell you how to repair the switch by just cleaning and oiling it. They also might tell you how to not get your eyebrows burned off by a capacitor.
Sash Guy
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