Hi All, I have bought some Kemet C878BF35460SA0J motor run capacitors for use in my RH84 V2 psu. It has four connectors and I am not sure how to connect it.
Can you tell me how to wire this capacitor? Is their a connector that I can order to make it easier or do I just soldier the connectors?
Also do I have to connect the bolt at the end to earth as it has an earth symbol.
Thanks
Can you tell me how to wire this capacitor? Is their a connector that I can order to make it easier or do I just soldier the connectors?
Also do I have to connect the bolt at the end to earth as it has an earth symbol.
Thanks
There is normally two pairs of terminals linked with a zero ohm link.
You can get the connectors and a cheap crimp tool from a motoring tool shop.
You can get the connectors and a cheap crimp tool from a motoring tool shop.
The anti-flashover barrier indicates which terminals are NOT connected together. If that is not obvious to you, determine which are connected with the diode/connectivity scale of a DVM.
The terminals are called .250" flag terminals. .250" female flag terminals can be bought at auto supplies (boxes of 9), electrical supplies (bags of 100) or electronics distributors (individual for a markup ). I recommend the insulated ones that will not short your amp if they pop off and touch each other.
Quality flag terminals ( TE connectivity, T&B Ideal Panduit 3M) will melt above 30 amps. The reason in motor service two such terminals are provided. The ones made in China will melt much lower. I scored an entire hot-rod at a bargain price because the builder was melting out the ignition terminal routinely with a 30 A load. He was using terminals from Radio Shack.
The terminals are called .250" flag terminals. .250" female flag terminals can be bought at auto supplies (boxes of 9), electrical supplies (bags of 100) or electronics distributors (individual for a markup ). I recommend the insulated ones that will not short your amp if they pop off and touch each other.
Quality flag terminals ( TE connectivity, T&B Ideal Panduit 3M) will melt above 30 amps. The reason in motor service two such terminals are provided. The ones made in China will melt much lower. I scored an entire hot-rod at a bargain price because the builder was melting out the ignition terminal routinely with a 30 A load. He was using terminals from Radio Shack.
You can solder them as well with proper wire.
Two sets of terminals are common in airconditioning work, it serves both as a terminal and capacitor.
The reason for that is that it is easy to swap out in the field.
There will be two U or flat C shaped terminals, giving two pairs of connection points.
Use proper terminations, solder only if you are fast (you can do damage if you heat the terminals too long).
So the sober advice above to use lugs is good.
I have used 6 square mm wires after soldering on my 1.5 Ton room airconditioner, on capacitors, American 5522 compressor, famous in its own field. Those pull 45A to start, 11A in run.
Kirloskar and Shriram both made them under license from Tecumseh at different points of time in India.
I was not able to get good quality capacitors with that type of termination, so I used the capacitors with single set, and used the top of the bad one as a sort of terminal point.
After that, was able to get Carrier service capacitor with terminals like above, so back to normal...
No ties to above named entities, just being helpful.
Two sets of terminals are common in airconditioning work, it serves both as a terminal and capacitor.
The reason for that is that it is easy to swap out in the field.
There will be two U or flat C shaped terminals, giving two pairs of connection points.
Use proper terminations, solder only if you are fast (you can do damage if you heat the terminals too long).
So the sober advice above to use lugs is good.
I have used 6 square mm wires after soldering on my 1.5 Ton room airconditioner, on capacitors, American 5522 compressor, famous in its own field. Those pull 45A to start, 11A in run.
Kirloskar and Shriram both made them under license from Tecumseh at different points of time in India.
I was not able to get good quality capacitors with that type of termination, so I used the capacitors with single set, and used the top of the bad one as a sort of terminal point.
After that, was able to get Carrier service capacitor with terminals like above, so back to normal...
No ties to above named entities, just being helpful.
Bolt may be for safety, or fixing to chassis, no idea about that.
And motor duty capacitors may be used for start and run, depending on the motor horse power, so I don't think you can call it a run or start capacitor.
My compressor has 36 uF for run, and 80-100 uF (alternate is 60) for start, through a hard start relay.
The alternate circuit can be 36 uF only, and the third version has both capacitors but with a PTC instead of relay.
200uF would be a start cap on a 3 - 5 HP compressor, but here in India we prefer to use 3 phase compressors for such work, as it implies a 2 Ton or larger compressor, those do not need a capacitor, and are more robust overall.
Carrier capacitor change was after 10 years or so, the old cap would not give enough jolt for start, so I changed both capacitors, and the relay...the machine was built here in 1992, at that time many 'assemblers' got 'kits', and built them.
It has a set of coils, fan and box for a 2T unit, the compressor is 1.5T, a combination proven here in our heat, which can go to 46C in peak summer.
The big coils help transfer heat when the smaller coils stop working in other machines.
Now it is all split units, mostly inverter drive, with power ratings almost half that of this one.
And motor duty capacitors may be used for start and run, depending on the motor horse power, so I don't think you can call it a run or start capacitor.
My compressor has 36 uF for run, and 80-100 uF (alternate is 60) for start, through a hard start relay.
The alternate circuit can be 36 uF only, and the third version has both capacitors but with a PTC instead of relay.
200uF would be a start cap on a 3 - 5 HP compressor, but here in India we prefer to use 3 phase compressors for such work, as it implies a 2 Ton or larger compressor, those do not need a capacitor, and are more robust overall.
Carrier capacitor change was after 10 years or so, the old cap would not give enough jolt for start, so I changed both capacitors, and the relay...the machine was built here in 1992, at that time many 'assemblers' got 'kits', and built them.
It has a set of coils, fan and box for a 2T unit, the compressor is 1.5T, a combination proven here in our heat, which can go to 46C in peak summer.
The big coils help transfer heat when the smaller coils stop working in other machines.
Now it is all split units, mostly inverter drive, with power ratings almost half that of this one.
Thanks for your replies, this picture seems to explain it well. Is this correct?
Also how do I tell which is positive and and negative?
Also how do I tell which is positive and and negative?
The top picture explains it perfectly. There is a plastic flashover barrier between the terminals that are not connected. Flashover is the external arc that occurs when a motor shuts off producing 1000-3000 volts, and the top of the capacitor is contaminated with salt from the sea, or pollen containing carbon from the air. A longer path for the arc resists flashover.
Do you not own a DVM? You should not touch capacitor terminals until your DVM proves the voltage is less than 1. The ohms/diode scale of the DVM will prove which terminals are connected. Beep or ohms<1 is connected. If ohms between 1 & 10 the DVM battery is probably low. If shorting the DVM leads together produces a number <10 but not 0, that number is the one that indicates the device under test terminals are shorted.
Polyprophylene and mylar capacitors are not polar. AC voltage is both plus and minus, 50 or 60 times a second.
Do you not own a DVM? You should not touch capacitor terminals until your DVM proves the voltage is less than 1. The ohms/diode scale of the DVM will prove which terminals are connected. Beep or ohms<1 is connected. If ohms between 1 & 10 the DVM battery is probably low. If shorting the DVM leads together produces a number <10 but not 0, that number is the one that indicates the device under test terminals are shorted.
Polyprophylene and mylar capacitors are not polar. AC voltage is both plus and minus, 50 or 60 times a second.
Last edited:
You don't. It's a non-polarized cap, as indianajo mentions above. Connect either way, it doesn't matter.
This will be used as C1 I suppose?
Thank again for the replies. Yes I will use it as C1 in the power supply section. I do have an RS digital meter rated to 1000v protection. I worked in the telecommunications industry as an engineer for 14 years and did some component level maintenance in the field at the time. However I had a change of career in 2001 so am a bit out of touch. So as I understand it I just connect all 4 tabs using the connectors as per the picture above and not worry about the polarity on this type of capacitor.
I think 2 tabs will suffice for a power supply, check the circuit again.
You need not use all four here, just one from each side, so two.
You need not use all four here, just one from each side, so two.
It you connect the rectifier to one set and run power out the other set you'll contain rectification current pulses to the first set of wires - probably beneficial - and you get simpler wire harnessing (and the ability to easily replug the amp power rails to a bench power supply for testing too).
Don't confuse him, please, Mark...
He can get away with one set, two will need color coding, and care if connections are broken and made again, easy to swap a set of wires if not marked. Then disaster will strike...
He can get away with one set, two will need color coding, and care if connections are broken and made again, easy to swap a set of wires if not marked. Then disaster will strike...
I guess it becomes clear by a closer look, even a closer look at the photo in #6: I bet there are two pairs of spade terminals, each one is riveted to the plastic base. So there are just two terminals actually.
Polarity isn't any issue with these motor capcitors, as they're designed to run on AC.
Best regards!
Polarity isn't any issue with these motor capcitors, as they're designed to run on AC.
Best regards!