0-260V 90A adjustable power supply problem

tonytong

0-260V 90A adjustable power supply problem [Copy link]

 

I think it's relatively simple, and the customer's requirements are not high. I do this: I use a three-phase contact voltage regulator. I am rectifying and filtering each phase of the voltage regulator output. That is to say, there are three 0--260V DC power supplies. Then I connect the three DC power supplies in parallel and supply power to a load at the same time. I don't know if this will cause problems in the next three years.

mass_lynnxy

The voltage regulation accuracy is not high and fluctuates with the mains. If the requirements are not high, it can be used. This voltage regulator needs a capacity of 30kW. . . .

tjw1666

The voltage regulation accuracy is not high and fluctuates with the mains. If the requirements are not high, it can be used. This voltage regulator has a capacity of 30kW.

dillinllp

Study, study . . . . . .

gmchen

Directly use a three-phase rectifier circuit, and the result is a DC power supply (not three), which has much smaller ripple than a single-phase rectifier circuit!

maychang

The author has not been seen since he posted this thread, and I don't know if he has built this power supply. Even if he has, he can't use a contact voltage regulator because he can't buy a contact voltage regulator of such a high power.

PowerAnts

maychang posted on 2017-1-12 07:25 The OP has never shown up since posting this thread. I don't know if he has made this power supply. Even if he has, he can't use a contactor voltage regulator because he bought...

That may not be the case

maychang

PowerAnts posted on 2017-1-12 09:30 That may not be the case

The last one is an inductive voltage regulator, not a contact voltage regulator. The first one, the hand-tightened terminals in the picture, look like terminals that can withstand 75A (not considering overload for the time being)? I think it's a bit mysterious. The brushes of the contact voltage regulator are its weakness. The reason why high-power voltage regulators are made into inductive voltage regulators is because the inductive type avoids the contact of the brushes.

PowerAnts

maychang posted on 2017-1-12 10:34 The last one is an induction voltage regulator, not a contact voltage regulator. First, the hand-tightened terminals in the picture seem to be able to withstand 75A (not considered for now...

If you want it to last for three years without breaking down, you can only use the inductive type. If you must use the contact type, at least use the 100KVA one, which has much better heat dissipation. The 50KVA one was just attached because I saw it. The size of the terminal is not clear. This is just a photo. I don't know the size without seeing the real thing, but sometimes intuition can deceive people. In general, I usually only use half of the capacity of the voltage regulator. I dare not use more. I have a customized 5KVA isolated AC voltage regulator, with an input of 220V and an adjustable output of 0-450V. The rated output current should be 11A. In fact, once I increased it to 8A, I smelled something wrong. From then on, I only dared to use it as 5A. I have been hurt.

PowerAnts

I bought a box of two-color terminal blocks before, with a diameter of 20mm and a nominal 50A. The actual temperature rise of 50A was about 20 degrees. The high-current terminals must be tightened before power is turned on. It is best not to turn on the power when the contact is unreliable. If you are not careful, the welding will burn, and if you are not careful, it will burn a piece of

maychang

PowerAnts posted on 2017-1-12 11:50 If you want it to last for three years without breaking down, you can only use the induction type. If you must use the contact type, at least use the 100KVA one, which also has much better heat dissipation. The 50KVA one is just...

The most vulnerable part of the contact type voltage regulator is the contact between the brush and the winding, which often burns the winding copper wire. When rotating to this point after the burn, the manual feeling is that this place is uneven and the rotation resistance has a sudden change. The copper wire is uneven, and the graphite brush wears very quickly. The repair method is to disassemble it and use fine sandpaper to smooth the burnt part of the copper wire.

PowerAnts

maychang posted on 2017-1-12 12:09 The most vulnerable part of the contact voltage regulator is the contact between the brush and the winding, which often burns the winding copper wire. After the burn, when rotating to this point, the manual feeling...

Looking inside the heat dissipation hole, the exposed copper part of the enameled wire is very clean, and there is no sign of burn. It is possible that the primary heat is too high, causing the paint of the primary coil to deteriorate. The isolation voltage regulator is composed of two layers of coils, the primary is in the inner layer, and the secondary is on the surface, and after polishing, it also serves as the voltage regulating winding.

maychang

PowerAnts posted on 2017-1-12 12:17 I looked inside the heat dissipation hole, and the exposed copper of the enameled wire was very clean, with no signs of burns. It is possible that the primary heat was too high, causing the paint of the primary coil to...

The rated voltage should be 11A, but it doesn't smell right when it reaches 8A. It is likely that the copper wire is of poor quality and contains too many impurities. Maybe it is copper-clad aluminum wire?

PowerAnts

maychang posted on 2017-1-12 18:17 The rated voltage should be 11A, but it doesn't feel right when it reaches 8A. It's very likely that the copper wire is of poor quality and contains too many impurities. Maybe it's copper-clad aluminum wire?

The coil of the contact auto-transformer usually has only one layer, and the electrical density is relatively large. I didn't notice this at the time, and asked the manufacturer to use a 10KVA iron core, first use a double wire in parallel as the primary, wrap it with insulating material, dip it in varnish and dry it, then use a single wire of the same diameter to wind one layer and grind the paint skin according to the method of conventional voltage regulators. After receiving the goods, I estimated the resistivity and it should be copper.