# Across the line motor starting



## MDShunk (Jan 7, 2007)

Can't say that I've ever volunteered motor data to the PoCo. :thumbsup:

I just looked it up for the main power company around here, and it's 50 amps LRA plus 14 amps for each additional horsepower over 2hp. When you get to 19.9 hp, you need special permission to start it across the line.... which is a bunch of crap. I've installed plenty in the 200hp range, started with conventional starters.


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## tates1882 (Sep 3, 2010)

MDShunk said:


> Can't say that I've ever volunteered motor data to the PoCo. :thumbsup:
> 
> I just looked it up for the main power company around here, and it's 50 amps LRA plus 14 amps for each additional horsepower over 2hp. When you get to 19.9 hp, you need special permission to start it across the line.... which is a bunch of crap. I've installed plenty in the 200hp range, started with conventional starters.


We don't either but when you want a new service drop they ask questions.


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## MDShunk (Jan 7, 2007)

tates1882 said:


> We don't either but when you want a new service drop they ask questions.


Yeah, I hear ya. Just tell 'em they're all on soft starts with a 10-minute accel. :thumbsup:


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## TOOL_5150 (Aug 27, 2007)

is "across the line" the same as line to line?


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## user4818 (Jan 15, 2009)

TOOL_5150 said:


> is "across the line" the same as line to line?


It just means starting a motor at full line voltage, which means that the motor draws a massive amount of inrush current which poco's really dislike. Hence the delta-wye starters (old school) or VFD's (new school.)

:nerd:


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## varmit (Apr 19, 2009)

Around here ( Duke Energy ) above 50 hp requires something other than across the line starting. The demand billing usually will not be affected by an individual motor starting, as the demand charge is based on the highest continuos 15 minute period for each month.

Yes, there are many places around here that go outlaw style and do not comply.


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## JRaef (Mar 23, 2009)

No two places are alike, it's something that is based on the available supply, distribution system and utility grid. When I was in Seattle, Seattle City Light required that any permit applicant get a sign off from them regarding motor loads. Anything over 15HP at 480V or equivalent needed a form filled out explaining how often it was expected to start etc.. So for something like an overhead crane in a 2 man shop, they allowed X- Line, but at a steel warehouse where the crane was used all day long, they required reduced voltage starting. A screw compressor at a tire shop that ran continuously and loaded/unloaded only was OK X-Line, a recip in a cabinet shop that turned on and off at random required RV. 

But right across the city lines where it was Puget Power, the rule was 50HP, hard and fast, no questions, but difficult to get a variance. Then in central Washington, it was 100HP because of the need for a lot of small irrigation wells, but if you asked for a variance for a 500HP river intake pump that only started once per year and ran for 6 months, they almost always granted it.


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## micromind (Aug 11, 2007)

Around here, when you ask for the available fault current study, they'll also give you the max motor HP that can be started across-the-lines. 

Generally speaking, the farther from a substation, the lower the HP. 

The power plants I've done were fed from either 120KV or 230KV lines; the max HP was usually over 1000.

I realize the locked-rotor power of a 1000 HP motor is huge, but it's less than 25 amps at 120 KV. 

There's a lot of 25 KV distribution lines around here; that raises the HP a lot.


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## John Valdes (May 17, 2007)

MDShunk said:


> Yeah, I hear ya. Just tell 'em they're all on soft starts with a 10-minute accel. :thumbsup:


Most of the POCO guys around these parts are much more informed than you make them out to be.




Peter D said:


> It just means starting a motor at full line voltage, which means that the motor draws a massive amount of inrush current which poco's really dislike. Hence the delta-wye starters (old school) or VFD's (new school.)
> 
> :nerd:


Hence "Wye-Delta" not "Delta-Wye". Are you a real electrician?


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