Bipolar NPN Transistor fails in conductive state

If that load is rated at 150W and it is designed for up to 24V system (assuming due to model number, DL24).
Then if the electronic load is PWM, then at max current, 100% duty, with 24V and 150W, it follows that;
I (current0 = Power / voltage

I = 150 / 24 = 6.25A

So if PWM, the load is pulsing 6.25A.
600mA will be a duty cycle of;
0.6 / 6.25 *100 = 9.6 %

The ZTX690B has these max pulse current rated as;

6.0 Amps

There appears to be no figure in the data for pulse duration and the load gives no info about what PWM frequency uses.

Tom.... :smiley: :coffee: :coffee: :coffee: :australia:

From Ali Express:

Electronic Load DL24

"The law of energy conservation". ???????
So 24V, 150W that I did the calcs for is quite possible.

We await the OPs reply to our many posts.

Tom... :smiley: :+1: :coffee: :australia:

[quote="Wawa, post:34, topic:884964"]

To turn off the transistor quickly you need to remove carriers from the base region. One way to do this is to apply a reverse voltage to the base connection. Or (less effective) you can ground the base.
Leaving it OC gives the carriers nowhere to go. so turn off is PAINFULLY slow, depending on the gain of the transistor. Trs designed for fast switching have low gain; this one has very high gain.

Also as @TomGeorge points out, we dont know how an "active" load will behave when the transistor is changing state.