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  • Help with Trouble-Shooting electrical

    Hey Guys,

    I’m trying to trouble shoot what I believe to be electrical problem with my lathe. Straight away, I will preface this post with the following; I know absolutely NOTHING about electronics.

    The following describes, the problem which I’m experiencing. For all purposes, my lathe is new. The circuit breaker, that’s housed inside the lathe, is “tripping” during machining operations resulting in electrical power loss to the lathe. I must re-set the breaker (inside the lathe) to restore electrical power. This usually occurs after 4 to 12 minutes of operation. To confuse this issue, though necessary, power is lost ONLY if the work light (carriage light) is illuminated and the spindle is turning. If power to the light is off, the lathe will turn for long periods without loss of electrical power. Also, if the spindle is not turning but the carriage light is on, I do not experience power outage. The two seem related.

    My lathe has a transformer and input terminals can be energized with either 220V, 240V, 380V or 400V. The transformer is currently setup to receive 220V. The output side of the transformer delivers 24V, hence the carriage light is wired for 24V and uses a 50W bi-pin halogen bulb. While living in the Lower 48, I did not experience an issue of power outage. I had reason to measure line voltage at my previous home because everything operated as designed. After arriving at my new location, I unpacked and commissioned my lathe. Shortly after putting my lathe into operation my carriage light “blew” and the bulb was replaced with the appropriate replacement bulb. It was then that I began to experience power outage. Also, I need to point out that after the move I had not operated the lathe to any extent other than to ensure all was operational. After replacing the bulb I put the lathe to task and power outages began to occur.

    I have attempted to trouble shoot this problem but I am so poorly educated in electronics that I really don’t know if I have found the problem. I measured my line voltage to the transformer and have found it to be 240V ….. not 220V. Is it possible that since the lathe is setup to run on 220V and line current is 240V, that magnetic relays or the transformer is getting hot causing the circuit breaker to “pop”? Have I found my problem?

    There are two other symptoms that I can describe which may add further light:

    1. When electrical power is applied to the lathe, a panel light illuminates to make one aware that the lathe has operational power. When the carriage light is switched to the on position, the panel light with dim. Conversely, when the carriage light is turned off, the panel light will be shine more intensely. This did not happen before my relocation.

    2. If the spindle is “powered up” and then the carriage light is turned on, a quick series of loud clicking sounds are heard for approximately 1 second and then all “seems normal”. Clicking is not heard when the light is turned off while the spindle is turning. This did not happen prior to relocating.

    For some reason I am lead to believe that too much current is being “pulled” when the light is turned on causing the magnetic relays to “rapidly click”.

    Have any of you electrical wizards got a solution to this issue? Am I on the right track when suspecting excessive line voltage being the culprit in light of the present transformer setup?

    Harold
    For those having fought for it, Freedom has a flavor the protected will never know.
    Freedom is only one generation away from extinction.

  • #2
    From my armchair, I would say that you have a problem with that transformer or the wiring for that light. When you turn on the light, it is causing the main voltage to the machine to drop significantly (indicated by the dimming pilot light) and this is affecting the actuating coils in the relays (clicking sound). As the volatge is dropping the current is increasing resulting in overheating the circuit breakers, resulting in the "trips". You could eliminate the 24vac machine light altogether, or try to find another 24vac light to hook up to the transformer. I'm guessing a bad transformer here though.

    Comment


    • #3
      Usually a 'slightly high' supply voltage is more desirable than a 'slightly low' voltage. You don't want to be running a motor below voltage as it will draw more amps and get hot (especially true if the low-voltage is due to a poorly-specced supply cable as that will get hot too and drop voltage further). Power (Watts) = Volts x Amps, so if you have a 1000watt motor designed to run at 250V it will draw 4A. Drop the Volts to 200V and the motor must now draw 5 amps to make 1000 watts.

      Sounds like you have a fault on your lamp TBH. If it is a work lamp supported on one of those flexi-spiral metal stems did it get severely bent in transit? If so it could have trapped a wire inside. I would get someone to run a test-meter over your machine to save you getting a potentially lethal shock.
      Peter - novice home machinist, modern motorcycle enthusiast.

      Denford Viceroy 280 Synchro (11 x 24)
      Herbert 0V adapted to R8 by 'Sir John'.
      Monarch 10EE 1942

      Comment


      • #4
        Power (Watts) = Volts x Amps, so if you have a 1000watt motor designed to run at 250V it will draw 4A. Drop the Volts to 200V and the motor must now draw 5 amps to make 1000 watts.
        I'm afraid t's not as simple as that. Some types of a.c motor can overheat under load on low voltages - but not because they feel morally obliged to put out the power stamped on the name plate !


        hwingo - If the mains voltage is 240 volts then why not first try setting the transformer tap to 240 volts and see if that changes the behaviour ?

        If the fault arose immediately after changing the bulb, it might be worth trying another bulb.

        Cheers

        Comment


        • #5
          I believe this to be the "key" to solving this problem:

          "1. When electrical power is applied to the lathe, a panel light illuminates to make one aware that the lathe has operational power. When the carriage light is switched to the on position, the panel light will dim. Conversely, when the carriage light is turned off, the panel light will shine more intensely. This did not happen before my relocation" note: edited for clarity by me.

          I bet the switch for the light is on the high voltage side of the transformer and that either the wiring for the light circuit or the transformer itself has a problem.

          Comment


          • #6
            2. If the spindle is “powered up” and then the carriage light is turned on, a quick series of loud clicking sounds are heard for approximately 1 second and then all “seems normal”. Clicking is not heard when the light is turned off while the spindle is turning.
            If this is the sound of a relay dropping out during the lamp warm-up surge, I would think it likely that the relays and the panel light are operating off the 24v secondary. The fault current would need to be very large to cause a sufficient voltage drop on the mains side to flick a mains relay...

            Cheers.

            Comment


            • #7
              Excellent observation Barrington, I'll bet you're right about one transformer supplying low control voltage and power for the light. I'm still visualizing a transformer issue...

              Comment


              • #8
                1) Barrington is almost certainly correct, since a multi-voltage machine would presumably have ONE control voltage, and 24VAC is fairly common.

                2) I am a little puzzled by the comment relating to "the breaker (inside the lathe)"...... any circuit breaker which is expected to open in use would be accessible. One that is "inside the lathe", unless it is simply behind a door, seems like one not expected to open except for "real faults" internal to the machine.
                Presumably this breaker is NOT on the mains, but a protective breaker for the 24VAC control voltage.

                3) the replacement of the lamp bulb seems to be associated with the problem. How certain is it that the bulb is identical to the original in type and wattage?
                If the bulb was of a higher wattage than the original, it might be that it adds up to too much draw on the 24V control voltage, or an inrush too high for the breaker.
                When the spindle is turning, several control relays are presumably "on", adding their draw to that of the bulb....... the combination may exceed the breaker rating

                4) Wiring for 220 and using 240 may not be a problem for the motor or the transformer itself. But the voltage to the controls will be a bit short of 10% high as well. The 24V will be about 26V, causing the relays and bulb to draw a bit more power, have a higher inrush current, etc.
                The result may go over the rating for a marginal breaker.

                5) The higher voltage may have "weakened" the breaker, which may now be more sensitive and open at less than its rating.


                Bottom Line:

                Wire the transformer for 240V, and try a bulb of a bit less wattage.... the 50 watts is a 2 A draw, and will have an inrush current (at the instant it is turned on) of between 15 and 20A, which is sufficient to explain the relay dropout that was mentioned (the clicking).

                If the problem persists, you may need to get a new breaker. If it were me, I would test the breaker, but you probably don't have a suitable way of doing that.
                1601

                Keep eye on ball.
                Hashim Khan

                Comment


                • #9
                  two things you might check

                  1 could the wireing in your new shop be under size.or a bad connection in it somewhere? to small a wire in the wireing,any extension cord,or a bad connection can cause this.check volts and amps when equepment is under power,it might show as good when it is not under power.

                  2 in moveing equpment sometimes the wireing gets enough viberation to loosen the connectins,or even break the wires inside of the insulation.these can sometimes be a bugger to find!

                  good luck

                  Comment


                  • #10
                    Originally posted by OKChipmaker
                    two things you might check

                    1 could the wireing in your new shop be under size.or a bad connection in it somewhere? to small a wire in the wireing,any extension cord,or a bad connection can cause this.check volts and amps when equepment is under power,it might show as good when it is not under power.

                    2 in moveing equpment sometimes the wireing gets enough viberation to loosen the connectins,or even break the wires inside of the insulation.these can sometimes be a bugger to find!

                    good luck
                    I agree.
                    I think you have magnetic starters with re-setable heaters. Not a "breaker". You may want to check the setting of the heater against actual amps drawn and the faceplate of the motor and or the transformer. The newer machines have a adjustable heaters. On older machinery heaters are not adjustable and some times go bad and need replacing.

                    I would check for loos connections first. Especially after a move.

                    Comment


                    • #11
                      since everything works fine if the light is turned off, i would suggest that there is no wiring problem.

                      i would check to make sure the "appropriate" light that you replaced the burned out light with, really is appropriate. it sounds like the light consumes more amperage than it is supposed to when turned on.

                      do you still have the old burned out one?

                      u may have installed a similar light, with the same socket, but works on a different voltage. if so, that would require more amps, if the lamp operating voltage was higher.

                      Comment


                      • #12
                        Hi Guys,

                        I apoligize for being so slow to respond. Ordinarially I'm faster to respond but they decided to work me a little longer than usual preventing me from responding sooner.

                        I do have a breaker circut inside the lathe as shown in the following image. To address the ease with which I had access to this control panel, I had to remove a fastened cover to gain access. Normally, this area is "off limits" with cover screwed in place. I had to capture this image by shooting into a mirror because the lathe is up against the wall and the panel is difficult to access.




                        Here is a schematic of the lathe.



                        I have had the opportunity to do a bit more testing and when the light is turned off the voltage at the transformer is 26.4 volts and when the light is turned on it's 23.3 volts.

                        I did replace the bulb with another but having the same results. I have spoken with the company from whom I purchased the lathe and I am using the correct bulb (24V 50W bi-pin 6.35 base).

                        The wiring to the light was not damaged during my relocation. I was caewful to build a wooden crate around the lathe to protect everything in the relocation process.

                        Vibration causing loose wiring terminals is a possibility since I did have to re-tighten some nuts and bolts on arrival.

                        When addressing the breakers in the above image, one can see a double throw breaker and a single throw breaker. It's the single throw breaker that's forever "tripping" requiring me to reach around behind the lathe and re-setting the breaker before power to the lathe returns.

                        Aside from breakers, I also have a row of magnetic coils beneath the row of breakers and transformer. Image shown below.



                        Hope this has been of help.

                        Harold
                        Last edited by hwingo; 04-07-2009, 11:35 AM.
                        For those having fought for it, Freedom has a flavor the protected will never know.
                        Freedom is only one generation away from extinction.

                        Comment


                        • #13
                          Sounds like you didn't change the heater current rateing when setting up the lathe to run on lower voltage.
                          re
                          Herm Williams

                          Comment


                          • #14
                            Originally posted by Herm Williams
                            Sounds like you didn't change the heater current rateing when setting up the lathe to run on lower voltage.
                            re
                            I haven't changed factory configuration ...... yet. Everything is as you see in the above images. I am actually running at a higher voltage because voltage to my lathe at this new location is 240V while the lathe is set at the transformer to operate at 220V (see image of transformer). On a different note, I am at a loss when you speak of "change the heater current rateing when setting up the lathe to run on lower voltage".

                            Harold
                            For those having fought for it, Freedom has a flavor the protected will never know.
                            Freedom is only one generation away from extinction.

                            Comment


                            • #15
                              From what I can see, the breaker is on the SECONDARY of the control transformer. and according to http://www.giniphil.com/chint.php is rated at 2 amps.

                              a 50w 24v lamp draws 2.08 amps by its self, never mind what the coils of the contactors draw which is probably 1/10 amp or so and you have 4 of them. it is no wonder that 2.4 amps (as a wild guess) is tripping the breaker, the 50 watt lamp alone is more than it is supposed to carry

                              I would strongly suspect that the lamp size should be 35 watts which would draw just under 1.5A check the lamp housing for a label denoting max size lamp


                              fred
                              Last edited by fredf; 04-07-2009, 12:14 PM.

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