mbrooke
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Page 52 onwards, WOW! :happyyes::happyyes: BIG thanks :happyyes::happyyes:
Does not have any line to neutral loads on the secondary help in any way in both these designs?
Pole top transformer impedance
- Thread starter ptonsparky
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Page 52 onwards, WOW! :happyyes::happyyes: BIG thanks :happyyes::happyyes:
Does not have any line to neutral loads on the secondary help in any way in both these designs?
mivey
Senior Member
Surges can also start on the POCO primary and appear on the transformer secondary so having no LN loads does not solve the problem.
mbrooke
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Ok, I was just thinking something along the lines of this, for better or for worse:
https://forums.mikeholt.com/showthread.php?t=198546&p=2000967#post2000967
mivey
Senior Member
All of our SC meters have spark gapsOk, I was just thinking something along the lines of this, for better or for worse:
https://forums.mikeholt.com/showthread.php?t=198546&p=2000967#post2000967
mbrooke
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SC?
Customer loads don’t make strikes worse. The issue is that pole grounds aren’t that great to begin with and act in a distributed fashion. Since utilities use wye-wye Z0 isn’t isolated. So all subs and customer grounds also participate and with better impedance to ground draw more current.
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mivey
Senior Member
self-contained
Julius Right
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- Electrical Engineer Power Station Physical Design Retired
According to ANSI Standard 37.010 TABLE 11 -Distribution Transformers-Single-phase secondary 240/120 or 480/240 and primary from 2400/4160 up to 24940/14400 V 25 kVA Z=2.4-2.6 %.
IMO, it's never a good practice to guess when it comes to transformer impedance! In fact, transformer values on sizes beyond 100kVA are values agreed upon by the manufacturer and the buyer; most of the time specified by the buyer. A 25 kVA transformer in front of me tells me the impedance is just 1.8%. Can't find answers why!:happysad:
Ignorant Scottie strikes again..............
Why would the mounting position make a difference to the impedance?
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Pad mount transformers are not as weight sensitive for design decisions?
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kwired
Electron manager
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It doesn't, but the fact it is designed to hang at the top of a pole might mean there are some differences between it and similar capacity unit not designed to hang at the top of a pole.
mivey
Senior Member
Different physical size/shape/configuration. Also, most 3-phase UG is in a single tank while OH 3-phase tends to be in separate tanks banked together.
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