sci.electronics.repair@googlegroups.com

Google Groups

etpm@whidbey.com: Jul 18 01:18PM -0700 Relative to my previous post today I need new starting caps for a 3 HP single pahse 230 volt motor. Dayton (Grainger) no longer has any info about this motor. The caps that blew were connected in parallel. One was 560-552 MFD and the other was 540-648 MFD. The caps were not original and they were from China. From looking on the web it seems like this much capacitance is a little high. The motor is an old motor. Maybe 40 years old. Maybe older. The cap housing is large enough for two caps and the wires connecting the caps in parallel looks exactly like the wires going into the motor from the caps. Same kind and color of insulation and same look from aging. So the big cap housing appears to have been meant to hold two round caps and not one big rectangular cap. Maybe it was hard to get as much capacitance in the same space years ago and that's why the two caps. If the capacitance is too high can that stress the caps enough to blow their guts out? Thanks, Eric

John Robertson <spam@flippers.com>: Jul 18 01:33PM -0700 > blow their guts out? > Thanks, > Eric   I would contact a motor rebuild shop and see what they recommend. They are the pros in this situation...   John

etpm@whidbey.com: Jul 18 01:40PM -0700 >blow their guts out? >Thanks, >Eric Well, I tried a smaller value, about 1/5 of what was connected before, and the motor tries to start but just can't. So I know I need more than 200 MFD. Eric

"Dave M" <dgminala@mediacombb.net>: Jul 18 06:10PM -0500 What's the model#/part# on the nameplate of the motor? Also, many nameplates specify the required capacitors for the motor. Have you looked there yet?   Dave M   <etpm@whidbey.com> wrote in message news:997vkdln3vdqi8b9ksdg6md0jidp7l6ams@4ax.com...

etpm@whidbey.com: Jul 18 05:13PM -0700 On Wed, 18 Jul 2018 18:10:37 -0500, "Dave M" <dgminala@mediacombb.net> wrote:   >> blow their guts out? >> Thanks, >> Eric   I looked up the motor number and Grainger, which sells Dayton Motors, no longer has data on the motor. Neither did an internet search yield anything. And the motor nameplate doesn't specify the caps. I though that maybe a newer Daytom motor would have the info but Grainger does not list the caps required for the motors on their website or on the motor nameplate. I can't understand why. Eric

Rheilly Phoull <rheilly@bigslong.com>: Jul 19 09:21AM +0800 > blow their guts out? > Thanks, > Eric   Not sure which model you have but the caps are shown as in series on this model ( Cap start - run ) https://www.grainger.com/product/DAYTON-3-HP-General-Purpose-Motor-6K145

Jeff Liebermann <jeffl@cruzio.com>: Jul 18 07:36PM -0700 On Wed, 18 Jul 2018 13:18:42 -0700, etpm@whidbey.com wrote:   Any reason for not disclosing the motor model number? Yes, I know it's 40 years old and Granger can't find it.   There are two caps in most such motors. One is the "starting capacitor". The other is the "run capacitor". <https://www.youtube.com/watch?v=qsuzfz5qcIE> <https://www.youtube.com/watch?v=OMd9QkinXz4> I'm fairly sure they should NOT be wired in parallel.   For 220VAC, the starting cap should be about 30 to 50uF/kW. 3HP(mechanical) = 2.2kW so try about 90uF.   The run cap is usually about 5 - 20uF.   For the starting capacitor calculations, see: <https://www.electricneutron.com/electric-motor/single-phase-capacitor-sizing/> <https://www.quora.com/How-do-I-calculate-capacitor-value-for-single-phase-motor> More: <https://www.google.com/search?q=calculate+motor+starting+capacitor>   I couldn't find anything on calculating the run capacitor.     -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

etpm@whidbey.com: Jul 19 08:43AM -0700 On Wed, 18 Jul 2018 19:36:47 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:   >More: ><https://www.google.com/search?q=calculate+motor+starting+capacitor>   >I couldn't find anything on calculating the run capacitor. The model number is 90653-N. The motor has only two wires coming out to connect to the caps, so there is no starting cap. I tried a known good cap that is about 200 MFD and it won't start the motor. The motor tries to turn and I bet if I took the belts off it would start spinning. The motor does spin easily enough but with the compressor load it takes so long to spin up with the 200 MFD cap I'm afraid the motor will overheat or the breaker will pop and so I turned it off after a few seconds. The compressor is a two stage air compressor that came with the motor as a set. The compressor is unloading properly so the motor is not trying to spin up a huge load and the motor has been spinning the compressor just fine for the last 40 or 50 years. I find it odd that there is no running cap but there just plain aren't connections for one. Eric

etpm@whidbey.com: Jul 19 09:14AM -0700 On Wed, 18 Jul 2018 19:36:47 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:   >More: ><https://www.google.com/search?q=calculate+motor+starting+capacitor>   >I couldn't find anything on calculating the run capacitor. Looking again I see that there are TWO model numbers on the motor nameplate. The top one is 5K483-D, which is a good number as I found it on the Grianger website. The other model number is on the bottom of the ID plate and it says Motor Model Number whereas the top model number just says Model. I have never seen this before. Anyway, I called Grainger because the cap(s) weren't listed. The guy at Grainger had to pull a file but he did find the caps and there are two. Both caps are 485-582 MFD and are wired in parallel. They are both start caps and the motor has no run cap. I have two cap coming tomorrow but they are 540-685 MFD. Will them maybe be a problem? In the meantime I will try to get the proper caps. Thanks, Eric

Ralph Mowery <rmowery28146@earthlink.net>: Jul 18 02:19PM -0400 In article <cimukdd379c0u1f6drl04036upm32qglv5@4ax.com>, etpm@whidbey.com says... > failed because of the extra work it had to do? > Thanks, > Eric   Could be.   Did you have any lightning due to stormes in the ares from the last time you used it ?

etpm@whidbey.com: Jul 18 11:46AM -0700 On Wed, 18 Jul 2018 14:19:18 -0400, Ralph Mowery   >Could be.   >Did you have any lightning due to stormes in the ares from the last time >you used it ? No lightning. It worked fine yesterday and this morning wouldn't start. The compressor is outside so I wouldn't be able to hear when the caps blew. So I don't know if they both blew at the same time or if one blew and then the other. The caps are 115 volt caps and the motor is 220 volts so each cap must be connected to one hot and the neutral. Which makes me think that the motor may have been running on just one cap for at least a little while. Maybe just yesterday. I don't know how old the caps are but I have had the compressor for 4 years and I bought it used. Eric

jurb6006@gmail.com: Jul 18 04:39PM -0700 Are you sure they're start caps ? Some 3 phase motors can be run with a cap connected the right way, those are run caps. What I have seen is they are usually rated double the input voltage, like if it is 220 the caps are 440.   Per your other thread, if they were 115 volts and in series you had like 200 uF, not ridiculous. High, but plausible. Even then the voltage rating is not high enough. If in parallel then you had like 1,000 uF which is very high, is this like a 5 HP or something ? In any case a 115 V cap will not take the voltage.

etpm@whidbey.com: Jul 18 05:20PM -0700 >Are you sure they're start caps ? Some 3 phase motors can be run with a cap connected the right way, those are run caps. What I have seen is they are usually rated double the input voltage, like if it is 220 the caps are 440.   >Per your other thread, if they were 115 volts and in series you had like 200 uF, not ridiculous. High, but plausible. Even then the voltage rating is not high enough. If in parallel then you had like 1,000 uF which is very high, is this like a 5 HP or something ? In any case a 115 V cap will not take the voltage. In my other post I corrected myself. The caps were wired in parallel. So the total capacitance is around 1000 MFD. Just for fun I tried a 200 MFD cap and it would not start the motor. The motor would just barely start rotating but I could tell it wasn't gonna come up to speed before something got too hot. What happens if the capacitance is too high? I think the phase will just get shifted too much which may cause hard starting. On the other hand I seem to remember that the starting cap doesn't just help with phase shift it also provides extra energy for starting so maybe extra capacitance isn't all that bad. I don't remember but would like to know. Eric

jurb6006@gmail.com: Jul 18 07:52PM -0700 A start cap is only in circuit during startup, it is switched out usually by centrifugal switch once a certain RPM is reached. Such a motor usually has more starting torque, but the cap is not right for efficient running.   A run cap is in the circuit all the time, and its value is important to efficiency and even running. If you take a run cap out of the circuit the motor will slow and slow and eventually stall under the load of the backpressure of the Freon. If you remove a start cap it can run forever but not start again.   Only larger systems use a start cap these days, and even 40 years ago. Got to remember this is 2018 and 40 years ago was 1978. Maybe more did back then but probably not unless it is like a 5 ton unit or bigger. (5 tons is 60,000 BTU) Is it that big ?   To find out, disconnect the cap while it is running. Use the one hand rule and insulated pliers, usually they have spade lugs and are not hard to pull off. Another way is that there will be no voltage across a start cap once it starts, but a run cap always has voltage across it. And put your meter on the 1,000 volt AC range.   But first you need the cap. Price them and see what kind of deal you can get on like a "set". Couple of 100s, 200s and 50s. Total that gives you 650. If the original even really is 1,000 that should at least started unless it has head pressure. (when the Freon is high pressure at the outlet and low pressure at the inlet)   I don't know the color comes for the wires, someone who does might but they won't work for free. You get into those things and you might have different voltages and maybe even speeds. Furnace blower motors have a gang of wires, and they are nowhere near a compressor motor.   Now, if you find it to be a run capacitor, somehow figure out how to measure current draw. Clampon ammeters are not expensive anymore, get the elcheapo Chinese kind. You have all these caps, and the optimum one will be the one that results in the lowest current drain. If with all of them in circuit the draw is lowest, go get like a 750. Then fine tune that. Keep throwing more and ore on there until the draw starts to go up. Once it gets past its peak back off. Well not peak but minimum. When you find the lowest current draw you have found the optimum cap value.   I don't now where you are but I am in the US and the last time I got motor caps it was from WW Grainger. If you have ANY company name, use it, the price changes. Five caps might be $ 20 each, that's a Cnote. If you get them cheaper it matters. Just remember they should be 440 VAC rated. Whoever put those 115 VAC caps in there should be flipping burgers.   Need to know if it is a run or start cap. If it is a start cap forget all I wrote. But I really think it is a run cap.

Stephen Wolstenholme <steve@easynn.com>: Jul 19 10:35AM +0100 >failed because of the extra work it had to do? >Thanks, >Eric   Did they fail at the same time? Some motors will start with one capacitor and don't fail until the last one blows. Years ago I had a job mending psus that had four electrolytic capacitors in parallel they worked until the last one failed.   Steve -- http://www.npsnn.com

Peter Jason <pj@jostle.com>: Jul 19 08:19AM +1000 I am unable to understand the intricate instructions on a Siemens "Chronogyr Rev15" con troller.   Can I simply bypass this unit and use a common household time clock instead.   I just need something to turn it on at 18.00hr & off at 21.00hr.   I care nothing for "zoning", etc etc   Please help.

tabbypurr@gmail.com: Jul 18 03:26PM -0700 On Wednesday, 18 July 2018 23:19:30 UTC+1, Peter Jason wrote:   > off at 21.00hr.   > I care nothing for "zoning", etc etc   > Please help.   A lot of CH systems do/did just that. You should find the relevant contacts marked slightly explicatorily.     NT

"Miguel Giménez" <me@privacy.net>: Jul 18 06:56PM +0200 El 27/06/2018 a las 5:52, Mike S escribió: >> check from time to time. Externally they are very similar.   > This site claims to offer the xr-m35 (no ez) for $4.99 > http://www.manualscenter.com/manuals/aiwa/xrm35ezhehrk-service-manual.html   I didn't get the manual, but the device is now fixed. The only remaining part is changing all rubber belts from cassette and CD spindle (the tray works OK).   Tip: a corroded FPC cable can be repaired just by cutting the damaged end, scratching the plastic isolation with a jacknife (not a cutter) leaving the last three millimeters untouched (so the copper tips don't lift when scratching) and then cutting the isolated end.   Thank you all.   -- Saludos Miguel Giménez

You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page. To unsubscribe from this group and stop receiving emails from it send an email to sci.electronics.repair+unsubscribe@googlegroups.com.