An Auto Transfer Switch for a home generator ...!

Discussion in 'The Projects Forum' started by hhhunzai, Dec 29, 2011.

  1. hhhunzai

    Thread Starter Member

    Nov 14, 2011
    72
    0
    Hello everyone!
    I want to make an ATS for a home, with two power supplies, One from the power supply company or DNO and the other from a 5.6KVA Generator.
    Gen set is, ELEMAX GENERATOR JAPAN: EX Series - Products Line up
    Model: SH7600EX.
    I am facing a problem with the DC section of the starting mechanism, I want to make it so that,
    it should start the generator in a few second automatically when the power supplying company does load-shadings due to unknown reasons.
    It should make at least three starting attempts till the generator starts with an interval of prescribed time.
    What kind of electrical timer of electronic circuit should I use for it.
    Generator is a 230VAC, but the starting mechanism is 12 VDC.
    The company supply obviously 230VAC.
    The reaming parts are understandable other-than the starting system, please guide me in this regards or please provide me a pictorial Idea for an electronic circuit.

    Thank you.
     
    Last edited: Dec 29, 2011
  2. hhhunzai

    Thread Starter Member

    Nov 14, 2011
    72
    0
    Please consider the case?
    I am in need please.
     
  3. ifixit

    Distinguished Member

    Nov 20, 2008
    639
    108
    Hi Hhhunzai,

    This is not an easy task to complete and still have a reliable and safe solution. You would be better off to buy an automatic transfer switch made for the job.

    That being said, here is a block diagram of some of what needs to be done. Refer to attachment.

    • Switch SW4 needs to be a proper transfer switch designed and approved for your application. Relay coils power by 12 volt dc would be convenient.
    • Transformers T1 and T2 isolate the hazardous 230VAC from the delicate control broad and human beings. The voltage is also reduced to 6 vac or so.
    • Use the UTIL ON signal to determine when the utility power has failed, or returned.
    • Use the GEN ON signal to determine when the generator is running properly.
    • The Ignition signal (IGN) comes from a small on-board relay and is used to stop the generator.
    • The start signal also comes from a small on-board relay an is used to power the starter solenoid on the generator.
    • The control board needs 12V DC from the battery which is properly filtered for noise & transients.
    • Use a micro controller chip to make everything work.
    • You could have a USB interface to the micro if you want to get fancy.
    Regards,
    Ifixit
     
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  4. hhhunzai

    Thread Starter Member

    Nov 14, 2011
    72
    0
    Nice idea, and I had thought about it, but it's not as much easy purchase it.
    The board which you are suggesting about is too expensive and the remaining accessories are extra.
    Therefore I want to make it by myself.
    I need an idea about an electronic circuit, which will be more easier and cheaper than the per-fabricated circuit board for me.
    I have a good idea about the remaining circuit and it is safe too as you may see here;
    http://www.motorstarters.co.uk/switchgear/automatic-transfer-switch/ats-r/
    but what I need is the starting mechanism with DC, to attach with this circuit.

    Please suggest em a solution that I would be able to make it my self.
    Thanks.
     
    Last edited: Dec 31, 2011
  5. ifixit

    Distinguished Member

    Nov 20, 2008
    639
    108
    Hi Hhhunzai,

    The block diagram I supplied in my post was a suggestion of what you needed to build it yourself. Details of the generator and transfer switch are needed before the control circuits can be designed in detail.


    Show a detailed schematic of what you have allready, showing the following:
    1. How do you sense when the generator is running and supplying 230VAC output?
    2. How do you sense the power company voltage?
    3. Transfer switch specification? Coil voltage?
    4. The generator starter circuit can be one of two methods: a) The switch grounds the starter solenoid, or b) the switch applies 12V to the solenoid. Which method does your generator use?
    5. How much current does the starter solenoid draw?
    6. Does the generator have an automatic choke?
    We'll focus on starting the generator first.

    Regards,
    Ifixit
     
  6. hhhunzai

    Thread Starter Member

    Nov 14, 2011
    72
    0
    I have attached the questions and answers for your questions.
    In the attachment there is a drawing illustrating the connections and information about your questions.
    please suggest me a solution relating to it.
    Thanks.
    HHH
     
  7. hhhunzai

    Thread Starter Member

    Nov 14, 2011
    72
    0

    Hello Mr. Ifixit,
    Please let me know if I can provide more details on subject.
    Thanks
     
  8. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    Something that frequently happens is people with no training have unrealistic expectations of what they can build or do. For example, you are going to loose your electricity for a little while during transfer, you simply don't have the equipment for anything else. Places like hospitals get around this problem by having equipment that is extremely expensive, a massive UPS of a sort, while the generator powers up to relieve the battery bank.

    The generator powering up is also an issue. Many generators do not have starters, you must pull the handle like a lawnmower to start the internal combustion motor. If the generator does not have the self start feature you are likely not going to be able to make one, without a machine shop I couldn't make one.

    So lets assume you have a generator that can self start off a battery with the push of a button. This also assumes it can do what it has to to automatically sequence the starter, including sensing if the generator motor did not start the first time and repeat the sequence. In that case all you would need is a simple relay. A really big, expensive relay.

    If you do not have experience with electricity you really need to get professional help, as in an electrician. You are not going to be able to get where you want to go without spending money, parts are not free and what you want are more expensive than most.

    Knowledge only goes so far, you are going to have to buy materials and components, and you will not be able to build them from scratch.
     
  9. hhhunzai

    Thread Starter Member

    Nov 14, 2011
    72
    0

    Mr. Bill,
    With all due respect, I am a well trained Electrician and an associate engineer too. And the Idea that I have attached is working for us with a Caterpillar automation relay. Don't you think you are telling me just an Unnecessary person.
    I am well trained in PLC systems, I can program them I can troubleshoot them and even can design and install a large industrial installation, I can work on any electrical system without prior experience.
    How can you say this idea an "unrealistic expectations" an untrained to me?????????????
    Is this forum is not for asking or sharing knowledge?
    If it is then please let me know, I will not ask questions.

    If I am asking questions it means I am sharing knowledge with all other members too,
    but you..............!!!!!!!!
    I don't understand your thinking.
    If you r a moderator it doesn't mean you have rights to say an unrealistic to a project.
     
    Last edited: Jan 6, 2012
  10. Georacer

    Moderator

    Nov 25, 2009
    5,142
    1,266
    Sharing bits of knowledge is easy through a forum. Training someone in one thread is next to impossible.

    Of course we don't, and cannot in any way, know your qualifications. We will take what you say as an honest answer to our queries.

    You have to understand, however, that we face many beginners every day, who are not properly trained to secure themselves from the dangers of electricity. We prefer taking things slow and safe than be sorry.
     
  11. ifixit

    Distinguished Member

    Nov 20, 2008
    639
    108
    Hi Hhhunzai,

    I'm looking at your schematic now. I missed your post yesterday.

    As I understand it, you can build, or already have, what is in the schematic right now. You just need help to change the starting logic to try 3 times only (with adjustable delays) before giving up. Is this correct?

    It is best to use a relay to activate the starter solenoid and then the control logic will just drive the coil of the relay. Another relay can be used to turn the ignition of and on as well.

    The signal into the logic, which indicates the availability of mains, or Generator, can be from a set of relay contacts.

    This task is best done with a micro controller. Do you know how to program one?

    I'll see if I can come up with a block diagram and flowchart to start with.

    Regards,
    Ifixit
     
  12. hhhunzai

    Thread Starter Member

    Nov 14, 2011
    72
    0
    Thank you Mr. Georacer,
    Yes you are right about the dangers of electricity.
    But don't be panic about me. I am working in this field since last six years.
    On single and polyphase systems, with low and medium voltages up to 11KV.
    I have enough expertise and knowhow about electricity.
    I am aware about the hazards and the safety precautions to carry out an electrical job.
    You are talking about training a person, I think this forum is about spreading knowledge and I am trying to gain knowledge in electronics circuit.,
    And the threads I discuss here are useful and every day usage in societies.
    Am I wrong about it ?
     
  13. hhhunzai

    Thread Starter Member

    Nov 14, 2011
    72
    0
    I really admire your appreciation and really happy about it.:)
    You understand me and figured out what I actually want.
    As you can see these diagrams are drawn on AutoCAD, I am an electrical expert but Not in ELECTRONICS. This is why, I am here.
    Coming to the point, yes you are right about starting logic, to try 3 times only (with adjustable delays) you are correct.

    I am totally zero in micro controllers, but learning the true basic of electronics right now. After that I suppose to learn micro controllers too.
    If you please really want to help me tell me a digital circuit, which I will be able to build myself through TTL ICs or CMOS ICs. I have good understanding of Logic gates and I am learning too.
    Thanks
     
  14. ifixit

    Distinguished Member

    Nov 20, 2008
    639
    108
    Hi Hhhunzai,



    The block diagram shows how things should be connected using small 12V relays to isolate Generator circuits from the delicate logic circuits.
    • Relay C2 supplies power to the starter
    • Relay C3 is for ignition circuit
    • Relay C4 is used to initiate a power switch-over from mains to generator or from generator to mains. You can decide how this will be interfaced with the KM1 & KM2 relays in your circuit.
    • A simple toggle switch is used to indicate whither the automatic start mode is enabled or not.
    • R3 contacts from a relay you supply tell the circuit if the mains voltage is present or not.
    • R4 contacts from a relay you supply tell the circuit if the generator voltage is present or not. I.E. the generator is running.

    The flowchart shows what kind of control logic, or programming is required.
    • Circuit reset starts at (A), & clears the attempt counter next
    • If in AUTO mode the logic checks that the MAINS are off for a period of time before attempting to start the generator. You decide the period.
    • Next the count is incremented, ignition on, starter engaged
    • The (B) sequence is a loop to monitor the GEN output and a 15 second timer
    • If the generator doesn’t start, the starter will be disengaged for a Delay(2) time and then go to (C)
    • It will go to (C) 2 more times if the generator doesn’t start
    • On the third attempt the ignition is turned off and the logic goes into a loop to monitor for the MAINS to return, OR the AUTO switch to be turned off.
    • Turning the AUTO switch off allows the operator to cause the start sequence to be repeated again if the AUTO switch is turned back on.
    • Of course if the generator starts then the starter is disengaged, wait for generator to stabilize, then switch from MAINS to GEN
    • The (D) sequence allows the controller to monitor the mains voltage returning and then switch back to MAIN and turn the generator off
    This would be best done using a microcontroller chip. To do it with discreet logic would be possible, but difficult and impractical in my opinion. What you are asking for seems simple enough, but requires a lot of logic sequences, timers and counters… and you are a novice in electronics.

    Is there anyone where you are that can help you learn, or do the programming? This forum, and others like it, can help you to learn logic and/or micros, but it is asking a little too much to supply a complete circuit, or program for your project.

    However, we can help a lot with; relay driver circuits, battery interface circuits, printed circuit board making, micro selection, NE555 timer circuit, voltage regulators, etc.

    Let me know what you think of this approach. How would you like to proceed?

    Regards,
    Ifixit
     
    hhhunzai likes this.
  15. hhhunzai

    Thread Starter Member

    Nov 14, 2011
    72
    0
    First Of all Sorry for being late to reply your post.
    Well, Thank you very much for your wonderful Ideas.
    I will initiate a digital circuit with timers, counter and other 74LS series ICs, first I will make a logic diagram or you may say a schematic for the circuit and we will discuss on it.
     
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