Start Capacitor Bleed Down Resistors

Start Capacitor Bleed Down Resistors - TEMCo Tutorial

Рет қаралды 46,373

11 жыл бұрын

View our full line of Start Capacitors: temcoindustrial.com/shop/capa...
Why do you need a bleed resistor on your start capacitor? Why are they important, and how do you size one?
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Пікірлер: 43

@vernroach3413 5 жыл бұрын

Very good explanation...As a former instructor, this would have been a great video to lead in with, when teaching capacitors.

@bol8lod 2 жыл бұрын

Thanks , finally got to know what that fuse is doing in my motor. because i have a damaged motor resistor

@derekdicus 9 жыл бұрын

Your videos have been very informative, along with the comments and your responses. Thank you.

@TEMCoIndustrial 10 жыл бұрын

Thanks for your comment. If your original capacitor didn't come with a resistor, you don't need to add one, though it couldn't hurt if you did.

@alfredcasasola 3 жыл бұрын

Awesome instructions. Thank you!

@tomvesco8692 6 жыл бұрын

Thanks so much for the very useful information!

@TEMCoIndustrial 10 жыл бұрын

Arcing internal to the relay would most likely require a voltage spike of well over 1000 V. As for what goes "kaboom," you are basically having a very rapid polarity switch inside the capacitor, which will result in excess heating. This can boil the electrolyte, causing a pressure build-up, popping the safety valve or the top of the cap. You can see what happens during over-voltage in our video titled "Start Capacitors & Run Capacitors for Electric Motors."

@steverobinson8123 10 ай бұрын

I have a dtable top belt sander that keeps blowing starting capacitors. There is no bleed down resister on the cap. How to calculate? 125v 300-360mfd cap. Motor is small probably 1/2 HP. Thanks for your great videos. They are very beneficial.

@miketooth8119 10 жыл бұрын

Very well explained

@hawkforce3109 3 жыл бұрын

very informative video!

@rooster658 4 жыл бұрын

You showed a 500 ohm 5 watt resistor. But you said it was a 5000 ohm 5 watt resistor. You said 240 volt positive swing and 240 volt negative swing. Are you referring to a 480v single phase circuit?

@TEMCoIndustrial 10 жыл бұрын

@Miguel Flores T. We do not carry a run cap in that size, though we do carry bleed down resistors. You may also want to try eBay to source that capacitor.

@Mishigoss55 8 жыл бұрын

Thank you for the tutorial, I found it to be of help to me. I am trying to rebuild my swimming pool pump/motor and want to bleed down it’s 2 capacitors so I can safely begin the repair process. The run capacitor is a 35 microfarad 370 VAC unit, while the start capacitor is 200 microfarads 110-125 VAC. The bleed resistor that I have is a 50 watt 330 ohm model. Is this appropriate for these capacitors? How long do you think it would take to bleed down the voltage on these? Is there any way of using ohm’s law to calculate how long it would take to fully discharge them? Thanks for your assistance.

@israelstinks 10 жыл бұрын

I asked this question on one of your other vids. My original start capacitor (216-250 mfd, 250 volt, on a Century 5HP motor on an air compressor) never had a bleed-down resistor. Should I add a resistor? Should I be concerned, since this came from the manufacturer (Sanborn) this way? I called TemCo and the man who I spoke with said that some start caps come from manufacturers without resistors, but didn't say if a resistor would might be helpful. Thank you!

@phillipbuttery7789 9 жыл бұрын

another brilliant tutorial for the non electrical minded ,I have been able to diagnose a fault and have realised what I need to purchase to effect a repair from my local supplier top marks

@israelstinks 10 жыл бұрын

Thank you. I guess by "safety", you mean safety from possible electrical shock. Can there be any other problems related to voltage retained in the start cap ... like maybe arcing somewhere in the motor's circuitry?.

@dfootballbeast 11 жыл бұрын

hello, quick quenstion; do run capacitors have a resistor in parallel for the same reason?

@salceti 10 жыл бұрын

I am trying to determine if my Craftsman Scroll saw motor is a capacitor start motor because I want to add a variable Speed control foot pedal. The recommendation for the foot pedal says not for use with capacitor start motors. Any help on this matter would be appreciated. So I do not want to purchase the controller if it will hurt the motor or be unsafe. thanks in advance

@israelstinks 10 жыл бұрын

I'll accept that since resistor wasn't originally included, then a resistor (apparently) is not needed ... but now you've said that a resistor "couldn't hurt". My question asked if a resistor might be helpful. I don't mind if you have to get "technical", but when you say "couldn't hurt", that's sort of ambiguous. I could add resistors to my bicycle, and it "couldn't hurt". Would adding a resistor help, and what value resistor would/should I add if adding one would help, please?

@gregstinogel2217 8 жыл бұрын

I have a 50V 68,000uf capt that I want to put a bleed resistor on. What value would you recommend?

@turiran2012 10 жыл бұрын

Hi do you guys carry a 30+15 uf 440V run capacitor with bleed resistor? I been looking everywhere & no hvac supply parts house has any even online I checked and nothing

@bigmacbricky4866 8 жыл бұрын

i have a heat pump and the start cap keeps going bad. it does not have a bleed resistor on it could that be a factor to why its going bad?

@loretocamilleri8480 3 жыл бұрын

Is a bleed resistor needed across a contactor coil?

@johnmurphy2642 3 жыл бұрын

Would a 15k ohm resistor, 2 watt be ok for a drill press 1/2 hp motor?

@baderfrdan447 3 жыл бұрын

Does the decrease in the resistance value between the common terminal and the start terminal imply that the compressor is malfunctioning? Example, the resistance between the common & start is 1 while the resistance between the common & the run is 1.3 (resistance total between run & start is 2.3). Noting that the compressor needs a start capacitor to make it running. Without that start capacitor, the compressor cannot work. So, two questions are here: 1. Do these resistance values indicate an issue with the compressor? 2. Does this need of start capacitor to start the compressor indicate that there is an issue with the compressor? Thanks

@strimbimmin328 3 жыл бұрын

I’ve heard conflicting reports on checking the microfarad rating on these capacitors, some guys say cut the resistor off and others say don’t cut it off. What’s the official say so?

@steveb8287 Жыл бұрын

My motor does not use a resistor. When replacing the capacitor, can I just cut off the resistor? What if I leave it on?

@TEMCoIndustrial 10 жыл бұрын

There wouldn't be any arcing in the motor circuitry. There are 2 main concerns with voltage in start caps. 1) It can shock the heck out of you. 2) Let's say that the cap cuts out at the peak of the positive side of the waveform. You now have ~ +240vdc stored in the cap. You turn off the motor, and go to start it again. When you close the switch, you happen to do so at the bottom peak of the waveform. That would be -240VDC measured from the 0 crossing....

@ppdan 7 жыл бұрын

hmm, If you turn off the motor, doesn't the capacitor get re-engaged with the motor and bleed thru the coil?

@djg585 4 жыл бұрын

Can not using a bleed-down resistor harm the motor?

@petersmith2481 6 жыл бұрын

Thank you for all your wonderful videos! I have a quick question on capacitor safety. As per your video, once the motor starts there will be an unknown amount of energy stored in the start capacitor depending on where in the wave cycle the centrifugal switch opens. However, once the motor stops and the centrifugal switch closes, won't the capacitor be re-added to the circuit and any stored energy in the capacitor dissipate through the motor windings? I just want to verify that under normal operation we would not expect any charge to remain in the start capacitor once the motor is turned off. Thanks in advance for any help.

@TEMCoIndustrial 11 жыл бұрын

No; run capacitors are never disconnected from the motor, so the residual voltage drains out through the windings. Start capacitors get taken out of the circuit and need a bleed down resistor to perform the same function.

@TEMCoIndustrial 10 жыл бұрын

It is helpful for safety reasons, but it will not affect your motor or start cap's performance either positively or negatively, as the resistor and start cap are only engaged in the circuit for a very brief moment.

@duncanmaina2965 3 жыл бұрын

I would like to how a copacitor start run motor is connected

@duncanmaina2965 3 жыл бұрын

Know*

@automan1223 7 жыл бұрын

explain to me if there is no charge in the start cap, when the compressor needs to power up how is this providing the juice to kick the compressor over ?

@shawnballee6053 6 жыл бұрын

automan1223 if you are talking about a residential ac compressor with 220 vac applied, the 220 is not single phase. it is actually two phases of 110 slightly out of phase with each other. The capacitor helps to develop torque by charging. this essentially provides for further phase shift between phases. In the case of 110 vac, the 110 vac motor has a start and run winding. Voltage is applied to both windings, but applied to the start winding through the capacitor, which gives the motor more torque by again shifting the applied passes to the two windings further out of phase. Bleed off resistor should be 1000 ohms or more (1000-1500) and 2-5 watts is fine..500 ohms is what was shown.

@israelstinks 10 жыл бұрын

"480 volts .... and kaboom!" Really? What goes "kaboom"? Are you providing accurate information here? It seems that if voltage was retained by the start capacitor, and if there was a relay in the circuitry, that the possibility of arcing might exist.. (?)

@TEMCoIndustrial 10 жыл бұрын

So you have +240 meeting up with -240 and now 480 V. Since the cap isn't rated for this... kaboom!

@johnconrad5487 7 жыл бұрын

it is not 240. 240 rms is 240x1.414 which peaks at around 340 Vpk

@AxelWerner 11 жыл бұрын

a "start resistor" ?!? :) u meaned a bleeding resistor.

@philg4116 2 ай бұрын

Bought some DPDT switches from TEMCO.. complete junk. The one I was using (bought the other as a spare) could not have had more than a hundred flips before it seized. Upon opening this was revealed to be due to one of the plastic cam things that are part of the one-piece molded rocker, and which had snapped off. Chinese-made junk. There's a reason they have historically used bakelite for nonconductive parts in switches, especially moving parts, that might be subject to heat from such as a contact made resistive due to arcing.. bakelite won't soften or melt. It will deteriorate over many decades, by which time it will have done its job.