Delta Voltage

[Ken9876]

We have a 480V to 240V delta transformer at a location that is feeding just heating circuits. Now I haven't looked behind the cover yet but I think it's ungrounded, I read 240 L-L, but my question is I'm able to read anywhere from 130-150 volts from line to ground, why can I read this if it's ungrounded?

 

[jim dungar]

We have a 480V to 240V delta transformer at a location that is feeding just heating circuits. Now I haven't looked behind the cover yet but I think it's ungrounded, I read 240 L-L, but my question is I'm able to read anywhere from 130-150 volts from line to ground, why can I read this if it's ungrounded?

There is no such thing as a truly ungrounded system. What you are reading is the voltage across the coupling capacitance between the line conductors and ground. The higher the impedance of your meter the higher the voltage you will read.

 

[Ken9876]

Thank you, I know it's ungrounded, because I know what voltages I'd see if it wasen't.

 

[infinity]

I bet an old solenoid type tester would read very little voltage to ground.