Air Compressor Wiring Befuddlement - Page 2
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  1. #21
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    The H30's mean the starter was previously running on 460.
    Now you propose to use H37's on 230. You already know that the rating is 3Hp for 230. If this was continuous closure then the match is not right. But for intermittent closure it might be ok. Would not be ok if you were sand blasting all day with the compressor running full out.

    The price of the heaters are roughly $22 (re-certified) to $29 (new) times three. I would take apart the starter and look at the condition of the points. If the points need to be changed out then you have to consider that and decide how much you have bonded with the the Furnas starter. The older Furnas stuff is what I would try to keep.

  2. #22
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    Quote Originally Posted by rons View Post
    The H30's mean the starter was previously running on 460.
    Now you propose to use H37's on 230. You already know that the rating is 3Hp for 230. If this was continuous closure then the match is not right. But for intermittent closure it might be ok. Would not be ok if you were sand blasting all day with the compressor running full out.

    The price of the heaters are roughly $22 (re-certified) to $29 (new) times three. I would take apart the starter and look at the condition of the points. If the points need to be changed out then you have to consider that and decide how much you have bonded with the the Furnas starter. The older Furnas stuff is what I would try to keep.
    Good point rons. The contacts probably could use replacement due to the age and use of them. They're not cheap though based on a brief search. I decided on the H37 heaters based on the charts shown below. The 5hp motor apparently draws about 14.4 amps, a little less than that on the motor data plate. It's a Product Class 14 in an enclosed closure that requires the use of Heater Table 134, which shows an H37 heater for the above amp rating. The compressor will eventually be used for my home shop and only intermittently. The reason for getting the compressor in the first place is to supplement or replace my current single phase 5hp/60 gallon compressor that struggles to keep up with a single air grinder, which I only use occasionally. I also recently purchased a small sandblast cabinet for small parts restoration.

    https://www.fs.fed.us/database/acad/...ter_tables.pdf

  3. #23
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    Quote Originally Posted by beeser View Post
    The contacts probably could use replacement due to the age and use of them. They're not cheap though based on a brief search.
    You can look around for point contact kits. They are available but look at yours first. Don't file the metal down but just use a brass bristle brush to clean them up.
    And if they are pitted be sure to keep them matched up in position. You want the hills and valleys to interfaced as before.

  4. #24
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    Default Motor Starter Upgrade

    Quote Originally Posted by rons View Post
    The H30's mean the starter was previously running on 460.
    Now you propose to use H37's on 230. You already know that the rating is 3Hp for 230. If this was continuous closure then the match is not right. But for intermittent closure it might be ok. Would not be ok if you were sand blasting all day with the compressor running full out.

    The price of the heaters are roughly $22 (re-certified) to $29 (new) times three. I would take apart the starter and look at the condition of the points. If the points need to be changed out then you have to consider that and decide how much you have bonded with the the Furnas starter. The older Furnas stuff is what I would try to keep.
    Myself, I would inspect the condition of the size 0 contacts first and clean them, if they were decent, I'd run them. NEMA starters are pretty tough.

    To be a purist there are many parts abounding to upgrade it, if you know where to look. Many times complete starters or contactors are cheaper than renewal parts. Here's some samples for a Furnace Size 1 parts units.


    FURNACE 18DP92BEFBT SIZE 1 MOTOR STARTER COMBINATION 30A 230/460V HMCP030H1C | eBay
    s-l500.jpg


    Furnas Size 1 27A 600V Motor Starter 40DP32A* series B | eBay
    s-l500.jpg



    Furnas Motor Starters | eBay
    s-l500.jpg


    (3) Furnas H37 Overload Heater Elements NEW!!! Free Shipping | eBay
    s-l500.jpg

    Many other brands to chose from as well for a replacement if necessary.

    SAF Ω

  5. #25
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    I do not use any of those old style overload heaters. This one is adjustable from 2.5 to 10 amps. I have another that is 9 to 18 amps.

    dsc_0806.jpg

    This one is like the one I have and it has two auxiliary contacts which add to the price.

    Furnas Motor Starter w/ Solid State Relay ESP100 pn#- 14DS+32A / 48ASE3M20 Sz 1 | eBay

  6. #26
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    Quote Originally Posted by SAF View Post
    Myself, I would inspect the condition of the size 0 contacts first and clean them, if they were decent, I'd run them. NEMA starters are pretty tough.

    To be a purist there are many parts abounding to upgrade it, if you know where to look. Many times complete starters or contactors are cheaper than renewal parts. Here's some samples for a Furnace Size 1 parts units.


    FURNACE 18DP92BEFBT SIZE 1 MOTOR STARTER COMBINATION 30A 230/460V HMCP030H1C | eBay
    s-l500.jpg


    Furnas Size 1 27A 600V Motor Starter 40DP32A* series B | eBay
    s-l500.jpg



    Furnas Motor Starters | eBay
    s-l500.jpg


    (3) Furnas H37 Overload Heater Elements NEW!!! Free Shipping | eBay
    s-l500.jpg

    Many other brands to chose from as well for a replacement if necessary.

    SAF Ω
    Thanks again SAF!! I ended purchasing the 3 heaters you mentioned. Odd that I didn't see it myself when looking for them. Everything should be golden now with the proper heaters. I'm in the process of positioning the air compressor just outside my shop, covered of course, and wiring it with a separate 40 amp, 3 pole breaker. I have a separate 3 phase panel coupled with my rotary phase converter. Hopefully the 40 amp breaker is sufficient as it's borderline or just over with the 3x FLA rule.

  7. #27
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    Quote Originally Posted by rons View Post
    I do not use any of those old style overload heaters. This one is adjustable from 2.5 to 10 amps. I have another that is 9 to 18 amps.

    dsc_0806.jpg

    This one is like the one I have and it has two auxiliary contacts which add to the price.

    Furnas Motor Starter w/ Solid State Relay ESP100 pn#- 14DS+32A / 48ASE3M20 Sz 1 | eBay
    Adjustable overload relays are convenient, but usually contain differential protection, or as some call it phase loss protection. That's not usually the best choice for use with a RPC . If the converter is not well balanced under load, it can cause nuisance tripping. Most IEC overload relays have differential included as well.

    I've had these units trip on utility supplied open delta 3Φ, due to the phase imbalance. One transformer pot being smaller than the others, voltage on the wild leg can drop under load. If the voltage is imbalanced, and the load is run for a length of time, the overloads can trip. It's really not a nuisance trip, but the relay doing it's job. But could be a pain for a RPC user, if not adequately supplied and balanced.

    SAF Ω

  8. #28
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    Quote Originally Posted by SAF View Post
    Adjustable overload relays are convenient, but usually contain differential protection, or as some call it phase loss protection. That's not usually the best choice for use with a RPC . If the converter is not well balanced under load, it can cause nuisance tripping. Most IEC overload relays have differential included as well.

    I've had these units trip on utility supplied open delta 3Φ, due to the phase imbalance. One transformer pot being smaller than the others, voltage on the wild leg can drop under load. If the voltage is imbalanced, and the load is run for a length of time, the overloads can trip. It's really not a nuisance trip, but the relay doing it's job. But could be a pain for a RPC user, if not adequately supplied and balanced.

    SAF Ω
    I run the phantom leg up through normally unused set of contacts. Never had a problem. Even during the balancing act. I like the wide range of adjustment too.


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