power transformer hook up
Let's say I have a transformer with 3 coils. When primary coil is connected to V, two secondaries output 12V. Wires are color coded, but I power transformer hook up know what colors stand for and there is no information about that on manufacturer's website. Is there any relatively easy way to determine which wire is primary, which is secondary and which is start to the secondary and which is end of the secondary coil?
In a step-down transformer, the primary winding will have a higher resistance. The power transformer hook up will power transformer hook up low, but there should be a noticable difference unless you've got a really big transformer. Transformer windings have a phase relationship, but it's typically not important for power supplies. Unless one of the wires has continuity to the transformer core, the polarity doesn't matter.
A relatively safe way to test transformers power transformer hook up to hook up a small AC voltage VAC and measure the voltages across the other windings. The primary's wire is thinner and as W5VO says has a higher resistance. For the secondaries I presume they're separated. To find start and end of a winding you measure resistance with your multimeter.
Depending on the transformer's rating you'll measure a few hundred ohms between begin and end power transformer hook up a winding. If you measure mega-ohms your measuring on two isolated windings. Let's say you can find windings A-B, C-D and E-F this way. To find the polarity power transformer hook up have the connect the primary to the mains. Measure the AC voltages of A-B, C-D and E-F. Let's say these are 19V, dating an older man 17 years and 12V.
Those are unloaded voltages, and especially for toroidal transformers those may be much higher than the rated voltage. In my example rated voltages might be 2 x 12V and 8V. Now connect A to C and measure the voltage between B and D. If this is 0V very low anyway A-B and C-D are in phase, so if A is the "start" of A-B, then C is the "start" of C-D. If the voltages are equal you can place them in parallel to double the current.
If the voltage measured between B and D was 38V the windings are in anti-phase: You can connect the windings this way to double the voltage or swap C and D to have the windings in phase again. You can do something similar with the third winding. Connect A to E and measure between B and F. If the voltage is higher than 19V still working with my example then you have connected the start of one winding to the end of the other.
Questions Tags Users Badges Unanswered. Electrical Engineering Stack Exchange is a question and answer site for electronics power transformer hook up electrical engineering professionals, students, and enthusiasts. Join them; it only takes a minute: Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top. How to determine which wire is which on a transformer? If you're trying to identify what a winding is, then here are some notes: If 4 or more wires have continuity, then you have a multi-tap transformer winding.
They don't necessarily have the same wire gauge. The primary winding of an N: So the resistance grows very roughly by the square of N. Would phase relationship have any impact if I want to connect two inner coils serially? Not necessarily, but if it's a step-down transformer, the primary will probably have a higher gauge thinner wire than the secondary if the wire is going to be different. In a step-down, the secondary has a higher current than the primary.
Yes, the phase will matter. If there really aren't any diagrams and you have two identical 12V secondaries, then you could hook them up "backwards" which would give you 0V in series. If you want to use them in series, connect the two windings in series and measure the AC voltage from end to end. If it's 24V, good! Otherwise, swap the wires of one of the secondaries.