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Old 05-20-2009, 03:51 PM
trognholt trognholt is offline
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Default applying 480 volts to a 440 volt transformer

I am in the process of hooking a used injection molding press and this machine was rated as a 220/440 volt machine. Our in plant power that I will be applying to thiis machine is 480 volts. That 480 volts is going to be applied to a transformer that is rated for 220/440 that drops the voltage to 100 volts for the controller power. My main questions are concerning the transformer and if this will cause the transformer to burn out and if I will still get the same 100 volt output or will this increase to due the higher applied voltage?
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Old 05-20-2009, 04:21 PM
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mik3 mik3 is offline
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The output voltage of the transformer will be 240V instead of 220V.

It will not be a problem because transformers are designed to be able to handle voltages around their rated values due to variations in the line voltage.

Is the voltage stable enough or does it varies a lot?
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Old 05-20-2009, 04:58 PM
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Originally Posted by trognholt View Post
Iand if I will still get the same 100 volt output or will this increase to due the higher applied voltage?
It will increase due to the higher voltage. At 480V in, the control voltage will be 109V. When the line surges to 500V (which is in keeping with specs for a 480V line) the control voltage will be at 113.6V. If your press controls can tolerate this, there is no issue. Maximum input voltage should be listed in the documentation for your press. If you don't have said documentation and cannot find it online, try contacting the press manufacturer.
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Old 05-20-2009, 05:11 PM
Slider2732 Slider2732 is offline
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Would be handy if there was an equivalent to logic circuits 7805 type voltage regulators.
78100 perhaps !
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Old 05-20-2009, 07:44 PM
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mik3 mik3 is offline
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Originally Posted by Slider2732 View Post
Would be handy if there was an equivalent to logic circuits 7805 type voltage regulators.
78100 perhaps !
It is an AC voltage, it much complicated to regulate it with solid devices.

Power companies have taps on the transformers and change them according to the line load.
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Old 05-21-2009, 12:51 AM
steinar96 steinar96 is offline
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Isnt there a risk of core saturation if the voltage per turn is exceeded. Unless the core is made with alot more turns then needed for safety.
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Old 05-21-2009, 01:19 AM
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Isnt there a risk of core saturation if the voltage per turn is exceeded. Unless the core is made with alot more turns then needed for safety.
There is but I think transformers can tolerate voltages between 10% of their nominal value.
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Old 05-22-2009, 05:54 AM
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THE_RB THE_RB is offline
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Transformers with light loads tend to overheat when the voltage is higher than spec due to the core losses. If your control circuit draws a relatively fixed current it is a typical industrial solution to put a series resistor to the power input to the transformer to drop the voltage 10% or so.
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