create a shore-gen-invertor-off switch using solid state parts

Discussion in 'OnBoard Electronics & Controls' started by sdowney717, Jul 28, 2012.

  1. BertKu
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    BertKu Senior Member

    Hi Lt. Kludge, If you had a similar design like CDK, my apology for arguing with you. I misunderstood you, I thought you suggested two contactors with a rotating switch instead of just 2 contactors.
     
  2. sdowney717
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    sdowney717 Senior Member

    CDK got a nice bright idea with this. :idea:;)
    Automatic switching of hot and neutrals depending on what is plugged in etc.

    One improvement for me would be having a toggle on the grid (shore) power coil. So would not have to unplug heavy power cord from grid power to run gen power, just turn off the relay coil.

    Boat is twin 30 amp power and I can easily find 30 amp DPDT relays like this
    Coil needs to be 120 V AC

    [​IMG]

    http://www.frys.com/product/1667853
    anyone have a link to something cheaper price and or higher amps?

    I already use a DPDT relay like this I bought at Radio shack to switch hot-neutrals for the charger-converter. Plug into shore power it is on, unplug and it will use the gen. Makes it very easy.
     
  3. sdowney717
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    sdowney717 Senior Member

    It does get more complex.
    I have twin 30 amp shore power cables.
    2 hots and 2 neutrals, hots are on different phases. It is like having 240V AC with 2 hots on different phases and a single neutral and boats have done this standard for decades.

    I have one generator hot and neutral at 6500 watts ~ 50 amps
    I have one invertor hot and neutral at 3000 watts ~ 30 amps

    So I think I must have more DPDT relays such as 4 for the grid (shore power) switching of hots and neutrals.
     
  4. sdowney717
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    sdowney717 Senior Member

  5. Lt. Kludge
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    Lt. Kludge Junior Member

    Manufacturer - Unknown
    Third Party Surveillance - none?

    Connectors 0.250 in. Faston tabs, which are rated for 15A?, on a 30A relay?
     
  6. sdowney717
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    sdowney717 Senior Member

    yeah, kinda not great. I have seen some USA type relays rated for 30 amp HVAC use with push on connections.

    here is one rated at 30 amps with push on connectors.
    Do you think the rating is wrong?
    http://www.spadepot.com/shop/Relay-DPDT-30AMP-120V--P8363C233.aspx

    better name?
    http://www.amazon.com/Potter-Brumfi...4008291&sr=8-1&keywords=30A DPDT relay 120VAC

    Cheap Packard Relay, I called them to ask what the amp rating is.
    http://www.amazon.com/Packard-PR341...4008344&sr=8-6&keywords=30A DPDT relay 120VAC

    Perhaps the Packard is similar to this.
    What do they mean when they say
    Number of Contacts 2, Contact Amp Rating 30 R, Contact Amp Rating 15 L, Contact Material Silver Alloy??
    http://www.amazon.com/Dayton-1EJG7-...008344&sr=8-14&keywords=30A DPDT relay 120VAC

    A poor review by a buyer!
     
  7. sdowney717
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    sdowney717 Senior Member

  8. CDK
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    CDK retired engineer

    No sdowney717, I meant serious relays, not toys. For this application you need something you need never worry about anymore.
     

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  9. sdowney717
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    sdowney717 Senior Member

    Do you have a link to the part ?
    I can see what will happen is, the prices of all the relays will approach just buying a manual switch.
     
  10. CDK
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    CDK retired engineer

    This is where the picture came from: http://www.ia.omron.com/product/family/1767/index_fea.html

    It need not be overly expensive. In the past I purchased several similar items through Ebay between $10 and $20, mostly products from AEG. All feature screw type terminals and a standard footprint for a mounting rail.
     
  11. sdowney717
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    sdowney717 Senior Member

    Am I reading the amp ratings properly?
    Too low?

    Rated carry current
    NO 40 A
    NC 25 A

    Inductive load is 10 on the NC at 480v AC
    Are they talking as in running inductive motors?

    If the contact is run at 120V AC, does this mean the contact can carry significantly more amperage current?

    Also coil voltage is DC 12 or 24.
    Seeing 4 poles available, current output from gen could be on the NC side and split across 2 poles hot and 2 poles neutral. So would be better then?

    Also only mentions DPST design not DPDT which sort of means it is not going to work? I thought this should be a DPDT design.

    Ideally a 4PDT reversing contactor with both sides rated the same amperage and a 120 V AC coil. Then all you need would be two reversing contactors.

    Otherwise, it would take more of the relays and a lot more control, it wont work like the diagram you show.
     

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  12. sdowney717
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    sdowney717 Senior Member

    Here is a 4PDT 35 amp rated open frame relay with 120vAC coil. Continuous duty

    Would need 2 to get it done, so up to $160 in price.

    http://www.grainger.com/Grainger/ST...cm_sp=IO-_-IDP-_-RR_VTV70300505&cm_vc=IDPRRZ1

    [​IMG]

    Problem is price keeps climbing yet still cheaper option than Newmar switch.

    What a mess, who knows what the relay amperage contact really is for this. Reading the TYCO datasheet claims it is 25 AMPS, but many web sites seeling the part says 35 AMPS, so who is correct?? Both, neither, anything goes, amps dont matter, etc....

    Different manufacturer lists different ratings, yet similar part number? Is this one made by TYCO, another by Potter Brumsfield, another by Struthers-Dunn?, all with different ratings?

    http://www.datasheetarchive.com/PM-17AY-120-datasheet.html

    Seeing I am dealing with a max of 30 amps, I would still likely use it.

    search for PM-17AY-120A lists
    https://www.google.com/search?q=PM-17AY-120A&sugexp=chrome,mod=11&sourceid=chrome&ie=UTF-8
     

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  13. sdowney717
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    sdowney717 Senior Member

    I got two of these struthers dunn off ebay for total $40 used relays. Seller sold it as a lot of two. I hope they are the same, the picture he showed looked the same as did the part number.

    http://struthersdunn.thomasnet.com/...-power-relays/pm-17ay-120-120vac?#Temperature

    Should work for this, rated up to 35 amps and price was ok. At some price point it is better to go one way or the other, this was decent.

    I plan to do a hookup similar to the original idea. I will put the gen on the default because it has an auto demand start feature that is load sensing.

    I will gang up the poles for the gen as it can output 6500 watts, so 2 poles will share the hot load, and 2 poles the neutral load.

    Invertor is only 3000 watt so only needs to use one set of switching poles which leaves the others unused or should i just hook them up anyway.

    Or perhaps some other useless task can be arranged for them. :p
    Will see how it goes as it gets wired up.

    It is better than what I have now, it still likely would not meet some code, regulation, rule, etc... somewhere deep in the bowels of some book a gnome would love.
     
  14. CDK
    Joined: Aug 2007
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    CDK retired engineer

    Yes, they look good and have 4 contacts so you can double the current capacity. All you need now is a sturdy plastic box around them and a "danger, do not touch" decal.
     

  15. BertKu
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    BertKu Senior Member

    Sdowney,
    Something to remember about relays and contactors. The manufacturer normally state the maximum current what is allowed to be switched on/off. If a contact is made and you have a decent quality manufacturer, the closed contact current can be higher. Logical not 10 times, but up to 20% is normally allowed.

    If the contact use paladium, even a higher percentage. Now my question to you: ARE YOU SWITCHING 6,5 KW ON and OFF or are you starting low and move up in power and also bring the power down and switch off then?

    The reason I ask, parallel switching of two contacts , under power should not be double, but double minus 20 %. The reason is that two contacts never closes at the same time, how small the difference may be, for that period, the full double current is on one contact.
     
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