Household outlet

Discussion in 'General Electronics Chat' started by maassmi, Nov 17, 2011.

  1. maassmi

    Thread Starter Member

    Oct 30, 2011
    81
    1
    I have recently built a small table top train layout for a Christmas display. I have had two transformers quit working on me. I have used the same outlet for these two transformers. I also have a 30 + year old transformer that works in this outlet, but is noisey and always has been noisey. I just purchased a multi meter and tested the outlet's output. It registered at 123 volts. This seems high to me for a household outlet. On the same breaker I have been powering my big screen TV, DVR, lights and computers and not had any othe problems. So, is there anything to worry about? Is there a way to reduce the voltage from this outlet so I don't damage my next transformer that is on its way to me in the mail? Thank you in advance.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    It sounds like you may have too many things on that one circuit.

    Can you write down the wattage, current, or VA rating of each item that you have on that circuit, and also tell us what the circuit breaker current rating is?
     
  3. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Hi maassmi. 123 volts isn't too uncommon. The voltage is generally between 100 and 125 volts. I'd go with Sgt. Wookie's theory that you're drawing too much current already. What happened when your transformers "quit" on you? Did they go up in a puff of smoke, or did they just stop working suddenly? What happens if you try to plug them back in?
     
  4. maassmi

    Thread Starter Member

    Oct 30, 2011
    81
    1
    When the first transformer died, the train did the hurky jerky for a while before all movement stopped. No noise or smoke from the transformer. The AC outlet side still works. The DC side died. On the second transformer, the train just suddenly stopped. No noise or smoke. Niether, the DC or the AC outlets have any power coming through. Someone suggested that I use a surge protector, but I don't understand how that would help. I am using a surge protector for my entertainment center (wide screen TV, DVR, BluRay and audio system. I also have a couple of lap tops plugged in as well as a few lights and our home security system. I have not experienced any issues with any of the other electronic devices.

    SgtWookie, it is nice to hear from you again.

    Mike
     
  5. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    What current rating does the train set need?

    Does it use AC or DC for input?

    What was the Volt/Amps of the previous 2 power adapters that died?
     
  6. maassmi

    Thread Starter Member

    Oct 30, 2011
    81
    1
    OK, here is a little more information: The Breaker has a "15" printed on it. I assume this is a 15 amp breaker. The transformers are rated as follows: First one that made the engine jerk around a while before dieing has the following rating: Input: 120V, -50/60HZ, Output: 17 VDC, 20 VAC, max output: 7 VA total; Second one where the engine just suddenly died without notice: Input: 120 V, AC60Hz, output: 19V AC 0-18VDC 5.5 VA. The train runs on the DC power. The engine is a new Athearn which was given to me this summer for my birthday, however, I have ran other engines on this layout of other brands while deciding on which train to run for the Christmas display. Also, the 123 Volt draw was happening in the late afternoon with most of the stuff in here turned on. This morning I tested again and even though it did reach 123 for a moment, the meter read 122.8 most of the time with most stuff in the room turned off. Then I got the idea to turn off the surge protecter that the entertainment center is plugged into. Then the reading jumped up to 123.1 and 123 mostly. The person from whom I purchased the second transformer suggested that I use a surge protector for the next transformer. Will this make any difference?
     
  7. maassmi

    Thread Starter Member

    Oct 30, 2011
    81
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    current required by the train? no idea. I know the light is rated for no more than 2 amps DC. The engine goes faster or slower based on how much DC power is sent to the track. I do not run the train at full power as this is too fast and the train can fall off the track at the curves when it goes too fast.
     
    gerty likes this.
  8. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Perhaps it is a problem with the built-in rectifier. Perhaps it was drawing more current than the diodes could handle?
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    Actually, what I was wondering is, what is the total watts or VA required by EVERYTHING that is plugged in? TV/entertainment center, laptops, lights, train transformers - all of it.

    Also, do you have any appliances that you operate on that circuit which are inductive loads, like a vacuum cleaner? You could wind up with large transients when those are turned off.

    It might be that you are simply overloading your transformers.
    Those are rather low-power transformers.

    It may be that you have some kind of wiring problem in your railroad layout that is causing a short, and overloading the transformer(s), causing them to burn up.

    A week or two ago we were fiddling with the CDU for the switch machines. If the regulator portion on the input of the circuit was not configured correctly (wired as shown in the schematics), you could wind up with a large current draw on the transformer.

    The CDU was designed to keep the average load on the transformer low, while giving your switch machines a short blast of current to get the points to move quickly.
     
  10. maassmi

    Thread Starter Member

    Oct 30, 2011
    81
    1
    HI, I am not using the CDU in question on this layout. I have one wire going to each of the two rails in the track from the transformer and they are not touching, therefore no shorts in the layout. I also have been using an older (30+ year old) transformer on this layout, but it makes a buzzing sound that I don't care for. This transformer has been making the same buzzing sound for its entire life and it seems to continue to work just fine. The newer transformers did not make the buzzing sound and I am looking to use another newer transformer that does not buzz.

    I have five light fixtures rated for 60 watts or less in the room. The three computers which we use have AC adapters that have an output of 19.5 V 4.62 A when in use. Only one was plugged in at the time. On the other devices I have plugged in I found the following bits of information: TV - AC110-120 V ~60Hz 240W, Blu Ray player - AC 120V 60Hz (22W)?, Bose sound system - 100-240 V AC, 50/60Hz, 300 Watt max, ADT alarm system - input - 120 V ac,320mA, output - 9 V ac, 3.3A. Even though we do use a vacuum cleaner in here, we hadn't used one in several days as I am lucky if the room is vacuumed once a month. I hope I have been able to provide you with the rest of the information that you want. I almost forgot ab3ut the WII game - Input 120 V, 5.3 W - 60 Hz, output 12DC 3.5 watts.

    Output draw on the old transformer: I just hooked up the old transformer and checked it while operating. While I have the train running at a comfortable speed the DC usage is around 5.5 and will flucuate by .3 to .5 with no noticable change in speed of the train. I also ran the train at 7.8, which was very fast and the output flucuated by as much at .8 with no noticable change in speed of the train.
     
    Last edited: Nov 18, 2011
  11. maassmi

    Thread Starter Member

    Oct 30, 2011
    81
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    going back to the CDU issue. I decided to purchase a commercial CDU from the same company that makes the turnouts and turnout motors that I am using. My mistakes get too costly.... got one on eBay for the same cost of the parts combined from Radio Shack. Should have done this in the first place. Retail is a little more expensive.
     
    Last edited: Nov 18, 2011
  12. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    You list the new transformers at 5.5 and 7 va, you didn't tell us what the va rating of the "old" transformer is. It sounds like you have tried some very undersized transformers. The output rating (va) must be equal to, or larger than the old one that works.
    As far as the 120 volt numbers, as DS8 stated 100 to 125 is typical. Do you have that circuit overloaded, possibly, but if it stayed overloaded the breaker would trip.
    Let us know what the va rating, or amp rating is on the old transformer.
     
  13. maassmi

    Thread Starter Member

    Oct 30, 2011
    81
    1
    gerty: The 5.5 and 7 Volts DC draw that I mentioned was the power output from the old functioning transformer while the train was running at two different speeds. The 5.5 was a good speed, the 7 was too fast. I touched the leads of the multi meter to the track and to the out put screws on the transformers and got the same readings. The transfomers that I have used, the broken ones and this very old one all have an input of 120 V ac.
     
  14. maassmi

    Thread Starter Member

    Oct 30, 2011
    81
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    Also, another thought: If the curcuit was over loaded, wouldn't the curcuit breaker in the breaker box "pop" and shut down?
     
  15. SgtWookie

    Expert

    Jul 17, 2007
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    If you have a heavy inductive load on the circuit that is suddenly turned off, you might wind up with a spike/transient on the circuit that might cause damage to your transformer.

    If you plug your transformer(s) into a surge suppressor, that will help to protect them. Many power strips have surge suppressors in them - but if they take a large "hit", like if lightning hits nearby, the MOVs inside the device can burn open - and you won't know that you are no longer protected.

    Your broken transformers may have burned out rectifier diodes in them, or (a) thermal fuse(s) that have opened up due to excessive heat. You might try unplugging them, opening them up, taking photos of the "guts" of the transformers and posting them so we can all have a look-see.

    Your old transformer is buzzing because either the windings or the core laminations are loose; most likely the latter. You may be able to stop it from buzzing by opening it up, and applying some shellac on the core laminations.
     
  16. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
    230
    The only thing I'd be concerned about on the AC side is a fire hazard from octopus outlets. Low voltage may indicate a poor connection that could overheat. But there is nothing suspicious in your AC.

    You train transformers are likely undersized in thier VA capacity. If you can, measure the old transformers current while running the train set. Times that by voltage, double, then buy a transformer with at least that VA rating.
     
  17. maassmi

    Thread Starter Member

    Oct 30, 2011
    81
    1
    The transformers are sealed with rivets and are not meant to be openned. The ones with plastic cases are frustrating me as well. I can not figure out how to get them open either. They don't just pull apart and there are not visible means of opening them.

    What can I do to protect my future transformer?
     
  18. RiJoRI

    Well-Known Member

    Aug 15, 2007
    536
    26
    Is the following correct?

    Identifiers:
    Transformers T0 (old), T1, T2
    Engines E1, E2, E3 (New)

    Operation:
    T0 worked with E1 and E2
    T1 worked with E1 and E2
    T2 worked with E1 and E2

    T0 worked with E3
    T1 blew with E3
    T2 blew with E3

    I would suspect that E3 is drawing more current (voltage here doesn't really matter) than the newer transformers can supply.

    --Rich
     
  19. maassmi

    Thread Starter Member

    Oct 30, 2011
    81
    1
    You train transformers are likely undersized in thier VA capacity. If you can, measure the old transformers current while running the train set. Times that by voltage, double, then buy a transformer with at least that VA rating.[/QUOTE]

    DC output during use was up to 7.8 volts DC... Times 2 equal 15.6. Rating on the transformer is 16.5. On the ones that broke down, the rating was 17 and 19. The transformer that gave out slowly was the one with a 17 VDC rating the one that gave out suddenly has the 19 VDC rating.

    I will be running the train at about 5.5 volts so I would need only 11 volts? The undersized transformers are being used well within their capability. Besides, all the model train companies that sell little "starter" sets which are the same size as this layout sell these little transformers with their sets and don't seem to have any problems.
     
  20. maassmi

    Thread Starter Member

    Oct 30, 2011
    81
    1
    RiJoRI:

    T(0) works with all E's;
    T(1) worked with E1, E2, E3, E4 & E5. Stopped working during use with E3;
    T(2) worked with E5 and stopped working while using E5. I decided on using E5 while T(1) was still in use;
    T(0) is in use and waiting for a newer replacement T(3).

    E5 is new and has less than 1 hour of use on it since putting it on the track. The other E's were much older, some as much as 20 years old with several hours of use and had only been cleaned a little and lubricated for use on this layout while I was deciding on which one to ultimately use for the Christmas display. If E5 were to draw more than 2 amps the light bulb would burn out and it has not burnt out.
     
    Last edited: Nov 18, 2011
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