Help Please - Step Down Transformer Is Still Tripping The Breaker

Discussion in 'The Projects Forum' started by SyY, Aug 7, 2009.

  1. SyY

    SyY Thread Starter New Member

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    Newbie to electric work here, so please bear with me. Just an average consumer who purchased an expensive piece of electronics in Australia that I now need to use here at home in the U.S. so I bought a Philmore ST-2000 Step Up/Step Down Transformer, going with the 2000 because the specs on the Australian machine say it draws max 1200 and I wanted to be covered.

    Problem is, it's working, but erratic. Panel lights dim up and down, transformer hums to the same pattern, and then bingo, circuit breaker trips. Sometimes it can run for a while, other times it trips after a few seconds.

    I basically have two problems:

    1) The first socket I was using is now completely dead since the initial circuit breaker trip, even after re-setting the breaker from the main box. And also dead is a set of seemingly connected sockets in a whole other room. Have I burnt out the wiring? The breaker? Both? What should I do to determine the extent of the problem/damage?

    2) Using another socket now (the Aussie machine is an unfortunate necessity), which has so far not fried out like the first, but the breaker keeps tripping. I can turn off the product and transformer, re-set the breaker, and turn on both and resume, but after a few minutes it will trip the breaker again.

    Help. What more do I need besides this $250 transformer to run this darn thing? I have checked this forum, and heard of things like "time-delay breakers". Wondering if I need something like this installed also? Is there some obvious missing step here? I thought the transformer itself would solve the issue.

    Any suggestions from you guys would be much appreciated. I am no expert in electronics, and if I need to bite the bullet and hire an electrician, I would at least like to have a clear understanding of what I'm up against.

    So thanks again in advance for any help!
  2. someonesdad

    someonesdad Senior Member

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    Do you mean the transformer is rated at 2000 W (2 kW)? Is the maximum load from the appliance 1200 W? This should be stated on the appliance's panel. Are you using the transformer to step the voltage up to 240 VAC?

    1200 W from a 120 VAC circuit is about 10 A of current. Your breaker is probably 15 or 20 A, so you shouldn't be overloading the circuit, unless perhaps if the appliance contains a 1 hp or larger motor. What is the appliance? We can give better opinions the more we know.

    If I were troubleshooting this, I'd first want to know what current this device is drawing at what voltage. Then I'd put a big pot I have on the circuit and see where the breaker blows. But this requires equipment you won't have, so you're probably going to have to call an electrician.

    Does the appliance and transformer show this behavior on a number of different circuit breaker's circuits? If so, I would suspect something is strange with the transformer and/or appliance. If it only happens on one circuit breaker circuit, I would take a closer look at that circuit.

    Did you have to wire the transformer yourself? If so, are you sure you got it right? It's possible you wired it backwards and you're trying to run the device on half of 120 instead of double it. This is easy to check if you have a voltmeter. Plug the transformer in without the appliance plugged into the transformer, then use a voltmeter to measure the output voltage. If it's not 240 VAC ± 20 VAC or so, then you've got a problem (I assume this device needs to run on 240 VAC).

    If you're not comfortable with making such measurements or don't have a voltmeter, you'd probably be wise to call an electrician.
  3. jj_alukkas

    jj_alukkas Well-Known Member

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    Your first room socket I guess has either a fuse or MCB which you missed out. Your wiring would never burn out as you have an MCB on that circuit. So dont worry abt it. Maybe your MCB has become faulty. Just give a check on the output of that rooms's MCB with a tester or voltmeter after resetting it.

    Your device problem needs few steps to troubleshoot. First disconnect your device and run the transformer alone and check for problems. If the problem starts only after the transfomer is loaded with the device, either, the transformer can't provide enough current at startup(if its an inductive load like a motor) or you have a voltage problem.

    The best way to confirm this is by measuring the current draw with and without load, but I dont think a normal multimeter will show the reading as most of them are 10A max.

    The last resort is an electician.
  4. studiot

    studiot E-book Developer

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    I don't know the details of US breakers (MCB), but in the UK we have 4 standards for each current rating, shown by a letter after the current rating.

    In order they will support decreasing inrush overcurrent at startup.
    So for a 16 amp breaker

    16D > 16C > 16B > 16A

    Normal domestic premises are fitted with B rating breaker.

    Equipment incorporating very heavy duty transformers or machinery often require the B version to be replaced with the C to prevent false tripping on start.

    The A version is used for special situations where we don't want even startup overcurrent, eg hazardous areas
    The D version is used in special industrial situations.
  5. SyY

    SyY Thread Starter New Member

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    First off, thanks very much for your replies guys!

    1) Someonesdad: I am using the transformer to step DOWN from 240 to 110 so I can use the Australian appliance here in the US. I did not wire the transformer at all, I am using it straight out of the box as instructed. Simply selected 110v on the back of the unit and plugged the appliance into the front socket (with an intermediate travel adapter to convert the Australian pins to US-style) and then plugged the transformer into my US wall socket. Does this affect your reply? Thanks

    2) JJ Alukkas: Thanks for putting me at ease about burning out the wiring. I was hoping not:) Can you define MCB for me? And no, the problem does not happen with only the transformer, but also it never happens on simple start-up of the machine, only during the middle of usage. Sometimes 15-20 minutes or so. But when it happens once, then it tends to happen again after a shorter interval of say 3-5 minutes. Again, I can flip the breaker and start again, but it persists in tripping the breaker after a few minutes. Again, I was assuming that the step-down transformer would take care of this, so I am confused. Do you think I need to replace the breaker itself with something a) heavier or b) time-delay breaker or something? c) do you have another suggestion? Thanks!

    3) Studiot: Again, the problem is not happening on start-up. It happens repeatedly after several minutes of use, say 15-20 minutes, and then once the circuit breaker trips, it tends to happen sooner after resetting, say 2-5 minutes, again and again. Does this affect your reply?

    Thanks again to you all for your help!
  6. someonesdad

    someonesdad Senior Member

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    SyY, a diagram of the electrical circuit you're using would be quite helpful. Is this on a 120 VAC or 240 VAC US circuit? To avoid making people try to figure out what a Philmore ST-2000 transformer is, it would be useful for you to explain exactly what it is (assuming you know yourself). I saw a picture of it here, but it's not clear what it is from the picture -- is it a device that plugs into a US 120 VAC outlet that then lets you plug in a 120 VAC or 220 VAC device? If so, is it an isolation transformer or an autotransformer? A picture of the interior would help or a schematic that came with the device.

    I assume the Australian device needs 220 VAC to operate, right? A quickie search of the web says normal mains power in Australia is 240 VAC 50 Hz. You'll need to educate us exactly about what the power, current, voltage and frequency requirements are, as well as what the device you're powering is. Otherwise, we'll be guessing. Don't just give a model number, describe what the device is and how it operates. Does it contain an AC motor? If so, what is the horsepower rating of the motor and the motor label's running current?

    If I was dealing with this problem, my first task would be to measure the load's voltage and current. Then I'd understand what's being dealt with. If you're running things on a 120 VAC US outlet, then you can characterize the load pretty well with a Kill-a-Watt meter. It will measure current, power, and power factor (but not start-up currents). They're handy because they're cheap ($20-$25), reasonably accurate, and can measure loads drawing up to 15 A. But they only work on 120 VAC circuits. A 120 VAC 15 A or 20 A circuit should be able to power a 10 A load indefinitely, but if it can't, either the load isn't 10 A like you think or there's something wrong with the power circuitry. I have my 120 VAC air compressor (a 1.49 kW load) on a 20 A breaker, but it blows the breaker occasionally (about 5% of the time it starts up), probably due to the starting current of the motor.
  7. SyY

    SyY Thread Starter New Member

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    Someonesdad: Ok, whoa, I'm going to have to do some research here to provide all that you're asking, so I will get on it. Meantime, thanks again for your reply!
  8. jj_alukkas

    jj_alukkas Well-Known Member

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    Sorry, an MCB is miniature circuit breaker. Seems like you have no problem on your electrical circuit and transformer. Problem lies in your device. Never replace your current breaker, with a heavier one unless you know what you are doing. You might burn your whole house. before you find a quick solution, you need to know what you are dealing with and what your problem is. Otherwise you would have investment after investment not knowing what your problem is. So as suggested by someonesdad, please explain what your device is and its ratings.
  9. Audioguru

    Audioguru New Member

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    That is backwards.
    You want to stepUP the 120V to 240V so that the 240V Australian device gets 240V, not stepDOWN to 60V.
  10. studiot

    studiot E-book Developer

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    This is not what you said originally.

    So is it a few seconds or 20 minutes?

    This is important because the difference would lead me to totally different diagnoses.

    Your original description suggests an classic inrush current problem.

    JJ - there is nothing wrong with replacing a 16 amp (or whatever rating) B rating breaker with a 16 amp C rating. this is correct and normal practice totally described by and within the regulations. Why do you think they have these categories of breaker?

    Your second description suggests an overheating problem with the building wiring/cabinet hardware. Perhaps you have cheap equipment fitted and operating it near the limits will seek out weakness.

    Don't forget that the the current draw at US mains voltages will be approximately double that of the supply to Australian equipment.
    Last edited: Aug 9, 2009
  11. SyY

    SyY Thread Starter New Member

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    Ok, forgive me if I am repeating myself but I may have just lost this reply right before sending, or I may be doubling this message:

    Sorry for any previous lack of clarity. Here are more details. The Australian product is a scientific water analysis and purification device. It basically takes water in from your tap via a tube connection, runs an analysis, ozonates the water and heats it to max 40c, and repumps it out (not forcefully). Since it is not currently on the market, I can only provide the limited information I have. Here is the listed "Performance Index":

    Power Supply: AC220v ±10%
    50Hz ±10%
    Overall power: 2000W
    Pilot switch for water pressure: ≥.10Kpa
    Ozone generating capacity: 200-300mg/h
    Ambient pressure: 4-38 degrees C

    That's all I've got and I cannot take apart the unit to take photos. The outside is just a clean plastic shell with intake and outlet tubes plus a single small backlit monitor screen. The power plug detaches, is made in China, is referred to as an XYA1L-10, and looks exactly like this (sorry for the super long link):


    http://images.google.com/imgres?img...firefox-a&rls=org.mozilla:en-US:official&um=1

    Studiot: Sorry for lack of clarity. Here's EXACTLY how things have gone down thus far:

    On the back of the Philmore ST-2000 Step Up/Step Down Transformer is a pin which must be set in one of several options (240v, 220v, 200v, 110v). I have placed the pin into the 110v slot. On the front, there are two 3-pin output sockets, one for 110v and one for 220v. I have plugged the Australian unit into the 220v socket using an intermediate universal plug converter I bought from a travel store to convert the Aussie pins to fit a standard US socket as available on the front of the ST-2000. Then, the ST-2000 has its own US standard 3-pin power plug, which I plug into my wall socket.

    I turn on the unit as follows: 1) turn on ST-2000, 2) turn on Aussie product

    The first several times (3-4 times) I used the product with absolutely no problem whatsoever, for a duration of approx. 45 minutes each time.

    The next time, after about 20 mins the breaker in my box flipped and the unit shut down. I turned off the ST-2000, flipped the breaker, started over and everything worked fine.

    The next time, same thing happened only now the sockets in both this room and one other room in the house are dead, even after re-setting the breaker.

    Since I unfortunately need to continue using the Aussie unit, I switched to an adjacent wall socket (which I had to access by connecting the power cord of the ST-2000 into a heavy gauge orange extension cord from Best Buy and taking it to the nearby other room's socket.

    The unit has ALWAYS worked on start up and continues to work properly on start up. But now, after anywhere from 2 or 3 minutes, to as much as 15 or 20 minutes, the breaker trips and I have to start all over. Also, now it seems that the ST-2000 sometimes creates a cycling sort of hum which corresponds to the Aussie unit backlit display monitor pulsing dim/normal/dim/normal/etc. Also, the shell of the ST-2000 definitely heats up, but this may have always been the case and I am only noticing it now that the problem keeps happening.

    The breaker-tripping does not seem to correspond to any particular function of the Aussie unit, meaning there is no turning on and off switches or anything during use. It is a simply and continuous heating/ozone/pumping process and no particular aspect of this seems to be the definitive trigger for tripping the circuit breaker.

    However, once the circuit breaker does indeed trip, it seems to trip again MUCH SOONER. For instance, during a particular session it may not trip for the first 20 min, but after re-setting it will trip again within 2-3 minutes or even less, and then same again and eventually I have to give up the session altogether. (some kind of overheating???)

    Ok, I hope this helps clarify things.

    AudioGuru: Sorry for my mix-up in my syntax. What you say makes complete sense. (except I guess I am stepping up from 110v here in the U.S., right? Stepping up from 110v to 220v for the appliance? So my question to you would be can you confirm that my process of connecting the ST-2000 is correct? Selection of 110v pin on back, and plugging in the Aussie unit to the 220v output female socket on the front. Does this sound right to you?

    So gentlemen, again thanks to all of you for your replies. I really appreciate your time and attention to my problem here. Thus far, I am thinking one of the following:

    1) The ST-2000 is malfunctioning after minimal usage and should be replaced
    2) The draw from the Aussie machine is erratic and therefore I must compensate somehow (but how?)
    3) There's some kind of overheating issue (and what should I do about it?)

    Any thoughts or suggestions? Concur? Disagree and think otherwise? And most importantly, suggestions of how I should proceed in order to remedy the situation.

    Thanks guys!
  12. SyY

    SyY Thread Starter New Member

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    Someonesdad: Thanks for your advice. I have posted more information just before this reply, so maybe you can take a look and tell me what you think. In the meantime, I will get a Kill-a-watt meter as you suggest. I suppose with this whole power conversion thing, I will still have to measure from between the transformer plug and the wall outlet, right? (Maybe this is dumb and once I hunt down the meter it will be obvious.) Thanks for your reply. Let me know if my previous reply provides the information you requested in enought detail.

    JJ_alukkas: Thanks for the definition of a MCB. So this is the circuit breaker in my main box, right? (series of breaker switches, not fuses)

    thanks again, everyone
  13. SyY

    SyY Thread Starter New Member

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    fyi guys, I did indeed post a very lengthy reply with spec details etc. but it has not appeared. I'm hoping it is being moderated, cuz my brief additional response below went through immediately. If it doesn't show up later, I will re-write the whole thing again.
  14. jj_alukkas

    jj_alukkas Well-Known Member

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    There is nothing wrong in replacing B with C but the OP said 'something heavier'.. By that I assumed of changing the amperage rating say 16 with 20. Is that right?
  15. Dave

    Dave Retired Moderator

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    Sometimes post get flagged by the spam system. I have approved the post and it is live on the forums. Apologies for the inconvenience.

    Dave
  16. nicsky

    nicsky New Member

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    If your transformer is right and you are getting 120V to 240V
    I think Australian pwr has 240Vac @10A =2400W in the us I think it is 120V @15= 1800w. Maybe you are just tripping your cct breaker because to much current is being used?
    One other thing, I once had a problem with a transformer designed for 60Hz being used at 50Hz. The transformer got so hot it shut down. This might explain why this happens after some time as it allows something to get hot enough.
  17. nicsky

    nicsky New Member

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    When you selectr 120v are you selecting this on the back of the amp?
    Seeing this is a device from china and is made for 220V I would not be supplrised if it could not be converted to 110V by changing the wireing of the transformer.
    se if there is a 110/220V switch on the unit
    If not open the unit ,find the transformer, find where the AC supply goes into the transformer, there may be 4 wires, If there is you can connect it so you have winding parrallel 110 winding series 220V .
    Or then again, some thng use a circuit called a Voltage doubler. This is normally controlled by a switch like you often see on the back of a PC.
    The moral of the story is, I bet it is easy to convert, because the chinese would not want to miss out on a large market of users on 110V unless there is some big technical reason.
    I have converted many items bought on ebay etc ( normall from 110 to 240) and have had no problems except for one time where i had to buy a replacement trasformer. to replace the one inside the unit.
    If you have to do this measure the outputs from the transformer an go a buy one of the same size and voltage from frys or similar
  18. jj_alukkas

    jj_alukkas Well-Known Member

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    There are 3 possible problems.

    1. The reason described above. You are drawing nearly 20A from a breaker on its verge. That makes the breaker in a point ready to cut any moment. In that case, get an ammeter or electrician, check for current draw and replace the breaker with a heavier one as u told before.

    2. Frequency problem. 110 is usually supplied a 60Hz while 220 at 50Hz. Confirm the frequencies you are working on currently is 50Hz. I think in US it is 60. If your device has a motor inside, it will stall and draw a heavy load due to frequency. A transformer will only give an output frequency equal to input. Current and voltage changes. f remains the same.

    3. Your Aussie device might be malfunctioning. After ruling out the first 2 possibilies, you can almost confirm this. From your description, a frequency problem might heatup the motor and then repeatetively fail after some runtime. Otherwise some internal component is heating up and causing the behaviour. You might need to get it serviced.
  19. studiot

    studiot E-book Developer

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    Well I think this description of function pretty well ties in with your fault record.

    The gadget goes through a series of stages in its operation. At some point the heater switches in. Perhaps this is faulty or marginal and overloads your supply?
  20. someonesdad

    someonesdad Senior Member

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    OK, SyY, we have a little more information to work with. Here's my guess at what's happening. The label says this is a 2 kW device. That's a fair bit of power to run off a 120 VAC circuit. It sounds like the load is resistive, not a motor. If there is a motor in there that's a major part of the load, heed the advice of others about potential problems due to frequency differences.

    One thing you haven't told us is the rating of the circuit breaker (or I've missed it). If it's 15 A, then if this device goes to it's 2 kW power level, the breaker will likely blow, as this is a current draw of 2000/120 = 16.7 A. If it's on a 20 A circuit, it shouldn't be blowing the breaker.

    But this applies to new equipment properly wired. In older houses, connections, outlets, etc. can degrade. My first concern is that you've had two outlets stop working. I'd want to know what went wrong with those outlets. Hopefully, the the problem is in the outlets. It's more serious if the problem is in the wiring. You may want to have an electrician troubleshoot this. I would also want to know what gauge of wire was used for the circuits that had the problem.

    One thing I would worry about is the size of the extension cord you've purchased. You don't say how long it is nor what gauge the wire is. If it was me, I'd want a 10 gauge extension cord. If the run was reasonably short (say, around 10-20 feet), I might consider a 12 gauge cord. Since you're in a marginal situation, you want to minimize power losses in the cord and a lower voltage at the device.

    The symptom you've described of working for a while, then blowing the breaker is consistent with a load that is near the breaker rating. The fact that it blows in a shorter time after reconnecting just means the breaker's components were already heated. The breaker seems to be doing its job.

    If I was in this situation, the first thing I would do is to get an ammeter in the circuit to see what the actual current draw is. One measurement replaces many suppositions. Forget the Kill-a-Watt meter, as it's only rated to about 1.8 kW. The most straightforward tool for this is a clamp-on ammeter, but it requires you to open things up if you don't have a current splitter. You can make a current splitter by getting an extension cord style plug and socket and wiring them with some 12 gauge solid wire. This makes the conductors accessible so you can clamp the ammeter around one of them to measure the current. However, this is getting into the area where you should be comfortable working with electrical power stuff, as a mistake can be hazardous.

    I would recommend you figure out how to get this device onto a 240 VAC circuit in your house. Unfortunately, this is likely going to involve an electrician running some wiring and assumes you have room in your panel for a two pole breaker. It's going to be much more expensive than just the $250 transformer.
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