Introduction to TTR Testing

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adamscb

Senior Member
Location
USA
Occupation
EE
Forum,

We have a TTR in our shop that I've never seen used, and we had an arrester blow on one of our power transformers, so I thought I'd get it out and mess with it. Got it hooked up to a 13,800 HV Delta to 480 LV Wye w/ Neutral transformer. For the V-Ratio I get 28.756, 28.757, and 28.759. For the T-Ratio I get 49.806, 49.809, and 49.812. Seems pretty good to me. Just a few questions I have are 1) is there a general rule of thumb in terms of TTR testing tolerances? I've heard 0.05 percent from theoretical but wondering if the forum has heard anything different, and 2) is it a requirement to unwire the transformer when doing TTR, or can the primary and secondary wires still be landed but obviously isolated from the source and load? Would this skew the testing results?

Thanks as always
 
ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
adamscb said:
Forum,

We have a TTR in our shop that I've never seen used, and we had an arrester blow on one of our power transformers, so I thought I'd get it out and mess with it. Got it hooked up to a 13,800 HV Delta to 480 LV Wye w/ Neutral transformer. For the V-Ratio I get 28.756, 28.757, and 28.759. For the T-Ratio I get 49.806, 49.809, and 49.812. Seems pretty good to me. Just a few questions I have are 1) is there a general rule of thumb in terms of TTR testing tolerances? I've heard 0.05 percent from theoretical but wondering if the forum has heard anything different, and 2) is it a requirement to unwire the transformer when doing TTR, or can the primary and secondary wires still be landed but obviously isolated from the source and load? Would this skew the testing results?

Thanks as always
Click to expand...

What is a TTR?
Obviously I won’t be answering your questions.:happyno:
 
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