Load Test on Single Phase Transformer

When I give you a circuit for a heavy transformer and you have a small one, it will die. Better tell me what you want to test. What transformer? Voltage, current, type. (separate windings or coils, tapped,?) Or do you want a universal load test, than you need a universal voltage, current, load. Your single phase transformer can be one of 10 grams or 1000 kg.

YES! Things like primary voltage, secondary voltage, rating (volt amps, kilo volt amps), what are you wanting it to do; without any information AT ALL we're forced to answer questions with questions.

The input voltage is 120 v

The output is 24v , 40 amp

Thanks for help.

120 Volts AC - 24 Volts 40 Amps.

Like types used in high power amps. I should go for toroidal wound transformers.

A lot more compact then the oldies. If you consider export. make your primary 2 times 120 and your secondary 2 X 24 Volts or 2 X 12 Volts too.

Connecting the primaries in series opens your 240 volts markets too.

A cheap way of testing: buy for 840 watts of car (truck) light bulbs. Put them in a metal box with some cooling, get a pair of dark sunglasses and start testing.

You can measure: temperature, current, voltage, voltage drop and if you wait long enough, life cycle.

For load wire wound resistors are probably best, but

Stainless steel banding straps or stainless steel pipe can be used for load.

If plain steel banding strap or pipe is used, load will be very inductive.

If load gets too hot, put fan on it, or if pipe is used, water may be run through it.

Is the pipe also considered as inductive load ?

When speaking of stainless steel, it is assumed that the stainless steel is the non magnetic type. Some stainless steel is magnetic and will be inductive the same as plain steel.

The inductance of stainless steel pipe will be the same as that of a copper pipe of the same dimensions.

At 60 hertz, a load made from stainless steel pipe should have insignificant inductance.

Thanks for your reply.

But i think the "wire wound resistors" could be considered more inductive than stainless steel pipe because it consists of multiple of turns.

You can use any kind of load. Problem is to know how much your load is.

I made a styrofoam cutting wire device with about the transformer you are talking about. The wire is regular welding wire from a MIG system. About 1m long and 1.2 mm thick. Regular steel 60. It is suspended in a U frame.

You can use this up to a certain level: once your transformer delivers too much current, the wire will get that hot that it melts.

In case you will use a stainless pipe, you need to know what you do.

Just patching up onto a piece is about a short circuit and has about NO inductance at all. It will only show to be a coil at very high frequencies (Mhz- see Lecher Line) (like a pipe of 1m with 2 connectors) If you go for a thin pipe (let's say 20 feet) with considerable length and coiled up, you have an inductive load, but not that high, unless you put a magnetic coil in it.

If the stainless is magnetic or not - it has nothing to do with the matter. Even the high power wire wound resistors on ceramic cores @ 60 Hz are not that inductive and considered - resistors.

If you do your tests uncontrolled (without e.g a variac) you will end up with a defective transformer or defective load. The least you can do is check the temperature, odor (burn) of your transformer and secure it with the right breakers for the tests.

There should be a written test protocol document for this activity, and a pass/fail boundary criterion established before the <...load test...> begins. That document needs to detail the procedure involved in carrying out the <...load test...>. The author of that document needs to advise.

Otherwise it isn't a <...test...>; it's a "demonstration" instead.