I was wondering if anyone can explain alternating current and alternating voltage polarity as it relates to time. If frequency is 60 Hz then I have 60 cycles a second. If a cycle is half positive and half negative then every 120th of a second I have current reverse and polarity reverse. Can...
I'm giving a metering class on 4 wire delta and one of the possible individual loads that may exists is a 208v load connected wild leg to neutral which yields a 208 volt 2 wire load. I just don't know if electricians wire in the breaker box for this load. It would be nice to say that it is...
I was wondering if customers ever actually use the 208 voltage (Phase to neutral) or is it just a mathematical voltage but not one actually used as a matter of practice? Any help would be appreciated. Voltages are 120/240/208.
peetey
I have a few questions about sychronous motors. I am a Journeyman Meterman by trade and we have some old mechanical meters on our system that use synchronous motors (rotors) as a timing mechanism for demand metering. I know that these are more frequency dependent. I am wondering if I have a...
When we have a garden variety 480 volt ungrounded delta service (secondary side) how is it defined by the NEC or in more technical terms? I want to have it defined technically as to distinguish it from other variations of 480 volt transformer arrangements. I like to be very precise about that...
I am a Journeyman Meterman by trade and an apprentice asked me this question and I normally get good responses in this forum. In order to sustain a current flow in the hot conductor there has to be flow in the neutral. If I have a current transformer and place two conductors with the same...
I like to think of vars as the "magnetizing or non-working portion of power" Generally vars are needed to establish the magnetic field necessary for inductive devices to perform work. Sychronous generators are pretty cool because of their abillity to vary the PF over a given range. As a...
I have a question about the current that the neutral carries under balanced 120v loads. I do realize that the neutral carries no current when there are 240v loads connected. I am pondering the 120v loads when they are exactly the same on L1 and L2. If I have 15 amps on line one and 15 amps on...
Could someone explain quickly how these work to create a neutral? Are they only tied to a ground? Are these considered to be grounding transformers? Under balance loading is the principle to carry zero current?
--peetey
We need this meter to be put on phone lines for an MV90 system and we need it to put out one pulse per mega watt either delivered or received. The meters we use cost around $3000 each so they will probably want only one that utilizes 4 quadrants. I just need to know that a summation ct...
I'm glad I'm speaking to someone who is familiar. I actually want to sum up two currents and output the combined to a meter element. We have a ringbus breaker scheme at one of our powerplants and it uses a 6 element meter. It is a very old mechanical type meter and it has to be replaced with...
There has to be someone who can answer this question or at least point me in the right direction. Is there someone who is an expert on current transformers or is even a little familiar with interposing cts or summation cts?
--peetey
I need to get some info on summation cts and their application. Is there anyone who has used these type of cts to sum up more than one secondary to one output? I was wondering which one I will need if I have 1000:5 cts in a powerhouse generator environment with coupling capacitors as a voltage...
I have another polarity driven question. Lets say I have a pole mounted ct on a single phase service, it is a standard outdoor primary CT. Now I have a choice of a single bushing or a double bushing pt. I choose the double bushing and now make the primary connections. I jumper down from the...
