1. not yet

2. seems so

Whatever components you use they should have correct circuit protection and ratings to suit the design.

Also lightening strikes can take any product out there is no absolute guarantee.

Why not show your circuit for discussion.

See page 5 for a schematic

http://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXyzxsu.pdf

Good one. I am working on Electronic load bank using PWM. That is Resistive load say 10KW resistor is fixed. I connect 48 DC to 60V DC to this resistor and very duty cycle so that I have variable "Constant Current" to test my source. Do you Any schematic? I am trying design with 3824/ 25 or TL494. Any advise?

Ask someone smart like Del Or Andy Germany

Or my namesake

Thank you, we must stop talking to ourselves it is confusing.

That link of yours was right on the button, I googled up a whole bunch of links in that area and there was some good reading, kept me busy for quite a while downloading.

The IGBT in that circuit has a protection back to back 365Volt zener diode across the IGBT,so while it is in circuit it should be OK, however Donald had his circuit in bits on the bench presumably without static protection. As he has not given much information it is difficult to comment much more.

Garth.

Hey Guys, Thanks for all the input..

This wasn't just a "Circuit" it was a whole new Dimmer Box, 2K that was designed to dim incandescent, CCFL, and CFL "Dimming" lamps, and it does a pretty good job of doing this.

I met the designer, and told him I had sent the unit back, because it failed.

He said, well we tested it, and it worked great?.. go figure.

All I know is, if I sell this to a bunch of Chicken Farmers, and they have a slight voltage leak, transients, etc, or if Lighting Strikes 1000 feet away, I am sure this dimmer would quit working.

Maybe it did work for them, or maybe they just fixed it, and they are trying to shut me up, so I won't hurt their sales.. Who Knows?

Whatever they case, it has me leery now..

Donald

If you wish to control your application with PWM I can recommend this kit https://secure.vividcluster.crox.net.au/jaycar2005/productView.asp?ID=KC5225&CATID=25&form=CAT&SUBCATID=588

It is quite cheap and to run the power you need you must build an off board heat sink with a suitably rated MOSFETs or IGBTs and supply them with the higher voltage you require. As you are using a resistance load the reverse emfs diode used for the motor drive is not needed.

I cannot give you the circuit for copyright reasons but this link gives you the source's so you might be able to ferret something out.

IGBT or FET based dimming has been around for quite a while. Unlike the posted schematic the circuit is usually realized by using 2 devices arranged in anti-series. The main reason to use this over conventional triac dimming is for capacitive loads such as electronic low-voltage lighting were reverse phase control is used versus standard phase control like you get with a triac. I have also seen this type of dimming in european dimmers that are "universal" in that they sense the load and can either operate in standard phase control for magnetic low-voltage lighting or reverse phase control for incandescent or electronic low-voltage. While IGBT's are certainly more ESD sensitive then a Triac more robust examples are out there.

Shawn

But Shawn....[in a whiney voice]

Post a schematic [or link to one]

Campbell lighting could help by telling us more, such as the brand.

He would like to know why the damm thing smoked from a little static & is this normal?

There probably a cmos with out proper protection involved.

Shawn,

what do you mean "reverse phase control"? Are you referring to switching on part way through a phase pulse and switching off half way hrough the pulse?

chas

Chas,

Reverse phase control is where you turn on at the zero-cross of the sine wave and then turn off sometime later. This obvioulsy is not possible with triacs as once they are on there is no way to turn them off as long as current continues to flow. This is why IGBT or FET's are typically used and either 2 devices are used or one in a bridge although the 2 device method seems to be much more common. This is better for capacitive loads as it reduces the inrush current of trying to charge the system worse for inductive loads.

Shawn

IGBT dimming works well with most all types of bulbs. They are especially useful when dimming CFL, CCF, and LED bulbs. IGBT dimming is usually reverse phase or trailing edge dimming. Triac or SCR dimming is forward phase or leading edge dimming. The IGBT dimmers fire at every zero-crossing point and the control cuts the sine wave off at the desired time according to the desired light level. This is why the new dimmable fluorescent bulbs will last much longer with IGBT type dimmers than triac dimmers.