Line side tap

[mwm1752]

It happens. We recently put in a 812kW PV system on the parking garage of a hospital. It is interconnected on the load side of the hospital's MDP.

what was the panel board rating???

 

[pv_n00b]

Except there is no load. With a parallel power system, you have two sources. This question is fairly common even among experienced electrical engineers and electricians when they first encounter an interactive system.

True, but I would hope the first encounter someone had with an interactive PV system was not also a 1MW project.

 

[pv_n00b]

I am working on a 1 megawatt system that involves a line side tap to a fused disc. switch. My question is should the tap conductors be run to the line or load side of the fused disc.?

Just a heads up, you will get dope slapped by some for calling it a line side tap. :blink:

It's a supply side or line side interconnection.

 

[ggunn]

what was the panel board rating???

4000A

 

[electrofelon]

Just a heads up, you will get dope slapped by some for calling it a line side tap. :blink:

It's a supply side or line side interconnection.

Gimme a break......From now on, no field jargon is allowed :roll:

 

[Smart $]

Gimme a break......From now on, no field jargon is allowed :roll:

I agree with giving us a break... but technically it is not just field jargon. How often are wire-type interconnect conductors of the size required for the entire service (i.e. splice rather than tap). Technically, service tap conductors are not defined. So one cannot apply the load side tap conductor definition.

 

[electrofelon]

I agree with giving us a break... but technically it is not just field jargon. How often are wire-type interconnect conductors of the size required for the entire service (i.e. splice rather than tap). Technically, service tap conductors are not defined. So one cannot apply the load side tap conductor definition.

And there is 230.46: service conductors may be spliced or tapped.

 

[jaggedben]

True, but I would hope the first encounter someone had with an interactive PV system was not also a 1MW project.

On the other hand, if one is looking for someone to do the AC side of a 1MW system, and the choices are an electrical contractor who has significant experience doing non-interactive hookups of the same power level vs. one who has a lot of solar experience but at much lower power levels, it'd probably be wise to go for the former. No?

 

[Carultch]

On the other hand, if one is looking for someone to do the AC side of a 1MW system, and the choices are an electrical contractor who has significant experience doing non-interactive hookups of the same power level vs. one who has a lot of solar experience but at much lower power levels, it'd probably be wise to go for the former. No?

If that is the case, and it were up to me, I'd hire the former to do most circuits 100A and greater and/or medium voltage where applicable, and I'd hire the latter to do the general array construction and wiring.

 

[jaggedben]

If that is the case, and it were up to me, I'd hire the former to do most circuits 100A and greater and/or medium voltage where applicable, and I'd hire the latter to do the general array construction and wiring.

Exactly. And the former guy is the one who would ask the OP's question.

 

[shortcircuit2]

Except there is no load.

No significant Load.

The inverters have nighttime power consumption.

The DAS use some power to gather information, many times connected to its own branch circuit.

 

[pv_n00b]

On the other hand, if one is looking for someone to do the AC side of a 1MW system, and the choices are an electrical contractor who has significant experience doing non-interactive hookups of the same power level vs. one who has a lot of solar experience but at much lower power levels, it'd probably be wise to go for the former. No?

It would be wiser to go with another choice. I'm not big on answering false dichotomy setups, which of these two bad choices are the least bad.
If I'm the developer of a 1MW PV project then I would hire people with experience in MW level PV systems. Blade direction is PV 101 level stuff. It's a legitimate question from someone getting started and maybe doing their first residential install. From someone doing a 1MW interconnection it makes me wonder what other PV basics they do not know.

 

[bob52]

thanks for your response

thanks for your response

Actually I am in agreement with the answers given unfourtionatley the Inspector of wires was not. I am hoping seeing all these responses will help to make the right decision on weather I have to rewire my disc.

It would be wiser to go with another choice. I'm not big on answering false dichotomy setups, which of these two bad choices are the least bad.
If I'm the developer of a 1MW PV project then I would hire people with experience in MW level PV systems. Blade direction is PV 101 level stuff. It's a legitimate question from someone getting started and maybe doing their first residential install. From someone doing a 1MW interconnection it makes me wonder what other PV basics they do not know.

 

[ggunn]

Actually I am in agreement with the answers given unfourtionatley the Inspector of wires was not. I am hoping seeing all these responses will help to make the right decision on weather I have to rewire my disc.

I'm a bit lost here. Are you saying that your inspector wants the inverter output conductors to be wired to the line side of your AC disco?

 

[electrofelon]

I'm a bit lost here. Are you saying that your inspector wants the inverter output conductors to be wired to the line side of your AC disco?

Yes, I am still confused. He should clarify exactly what conductors and disconnects he is talking about.

 

[310 BLAZE IT]

Similar to how I've asked how to know which side to call primary vs secondary of a backfed transformer. Obviously I know what primary and secondary mean in general, but when aren't building a conventional system where power only flows from the utility, it isn't as simple to choose your vocabulary.

Someone on solar cmp please define these terms I find it very frustrating to clarify this to anyone who I'm talking to



Sent from my SM-N920V using Tapatalk

 

[310 BLAZE IT]

what was the panel board rating???

I did the same with a 5000a panel board. Made sure to adjust the main plugs to 3200a because it no longer needed the capacity.

Sent from my SM-N920V using Tapatalk

 

[ggunn]

Someone on solar cmp please define these terms [primary and secondary of transformer] I find it very frustrating to clarify this to anyone who I'm talking to.

Unfortunately, there is no uniform way to look at this. Some schools of thought call the higher voltage side of a transformer the "primary" irrespective of the direction of current flow. Others consider the "uphill" side of current flow to be the primary.

To try to avoid confusion I usually refer to them as the high and low voltage sides of the transformer, which works unless the transformer is a uniform voltage isolation transformer, in which case all bets are off.

 

[GoldDigger]

Unfortunately, there is no uniform way to look at this. Some schools of thought call the higher voltage side of a transformer the "primary" irrespective of the direction of current flow. Others consider the "uphill" side of current flow to be the primary.

To try to avoid confusion I usually refer to them as the high and low voltage sides of the transformer, which works unless the transformer is a uniform voltage isolation transformer, in which case all bets are off.

For many purposes the most useful way to designate the primary is that it is the winding which is first energized when the transformer is connected.
Not the first one to be connected, but the first energized and therefore the winding that supplies the inrush and magnetizing current.

 

[JasonC]

Lets Break this down simply.

Lets Break this down simply.

I am working on a 1 megawatt system that involves a line side tap to a fused disc. switch. My question is should the tap conductors be run to the line or load side of the fused disc.?

Lets remember all the equipment is still energized even when the PV is not producing power.

"line side tap to a fused disc." So you are energizing a set of conductors prior to the OCPD associated with the Feeding conductors (Between the meter and main.)

"should the tap conductors be run to the line or load side of the fused disc.?" Those conductors must go the line side of the Solar disconnect, if not your going to get surprised when you go to replace the fuses for the PV array as the fuses will be energized as well as the blades.

Think about the next person that is going to work in that equipment that has never seen solar.