dmalkokian
Member
- Location
- Brooklyn
- Occupation
- Electrical
Should the voltage of L1/N and L2/N sum to the same voltage as L1/L2? I heard it has be a factor of square root of 3
Should the voltage of L1/N and L2/N sum to the same voltage as L1/L2?
- Thread starter dmalkokian
- Start date
- Location
- New Jersey
- Occupation
- Journeyman Electrician
You have to tell us what system is being used? For example single phase 120/240 or 208Y/120?
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Yes, but the two voltages must be added vectorially, not arithmetically.
As infinity said, the √3 comes into play with 3-phase systems.
dmalkokian
Member
- Location
- Brooklyn
- Occupation
- Electrical
It’s single phase. L1/N and L2/N was 110v. But L1/L2 was 186v. Just trying to understand the calculation behind it.
dmalkokian
Member
- Location
- Brooklyn
- Occupation
- Electrical
I was testing by an equipment. The building is on 3phase but the equipment needed only single.
Well if it is in fact single phase you have a problem.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Are these measured voltages or just numbers from a calculation? If there just from a calculation there is no such thing as 110 volts.
Ok, you are probably reading the high leg of a wye system.
dmalkokian
Member
- Location
- Brooklyn
- Occupation
- Electrical
It’s measured in field with a multimeter ( estimated reading but accurate)
- Location
- New Jersey
- Occupation
- Journeyman Electrician
So the building is 3 phase 208Y/120. Phase to phase is 120*1.73. The correct voltages should be 120-N, 208 phase to phase.
dmalkokian
Member
- Location
- Brooklyn
- Occupation
- Electrical
We were authorized to test the equipment only. The onsite electricain said that the whole building was receiving 186v.
dmalkokian
Member
- Location
- Brooklyn
- Occupation
- Electrical
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Well that's a problem. Was that measurement taken at the service? That would be the only way to determine if the utility was providing the proper voltage.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
As others have said, the sqrt3 only comes into play if it is two legs of a three phase service you are measuring.
dmalkokian
Member
- Location
- Brooklyn
- Occupation
- Electrical
Yes the equipment wouldn’t function due to under voltage protection. Was just curious on the calculation of getting 186v between L1/L2
dmalkokian
Member
- Location
- Brooklyn
- Occupation
- Electrical
Where do get 1.73 from?
The square root of 3
- Location
- New Jersey
- Occupation
- Journeyman Electrician
In a 3Ø Wye system the phase angle is 120°. The 1.73 which is the √3 is derived from that angle.
How to Calculate Three Phase Values? - Study for FE
Read this detailed PE Power and FE Electrical preparation guide on how to calculate three-phase values.
www.studyforfe.com