Dc Drive (penta Kb Power

HI EXPERTS

I KNOW SOME OF YOU EXPERTS ARE PRETTY KNOWLEDGEABLE ABOUT AC& DC DRIVE
CAN YOU KINDLY EXPLAIN WHAT ARE THE TERMS :
1 REGENERATE TO STOP

2 COAST TO STOP

I WOULD LIKE TO THANK RS DORAN FOR HIS HONEST RESPONSE AS WELL AS PARAFFIN POWER REGARDING MY PREVIOUS POST CONCERNING ON LINE EDITING
I WILL BE BACK WITH FURTHER QUESTIONS.

MANY THANKS EXPERTS

I am going to give a couple of examples, first coast to stop, imagine yourself in a car on a flat road and you take your foot off the gas pedal. The car will slow down and eventually coast to a stop.

Regenerative example would be like an eleveator going down, gravity would easily allow the elevator to fall so the motor has to "hold" the elevator in position. What happens is the motor can act like a generator when the speed exceeds the commanded speed and the resultant feed is fed back to the bus. That is what is called regenerative.

There are many other demands besides vertical loads like an elevator that can call for regenerative braking. Basically its the motor acting to brake itself depending on application/situation.

As is typical of everything having to do with drives, the terminology can be tricky. Whenever you use the motor as a brake to decelerate the load quicker than it would naturally coast to a stop, in DC that is called dynamic braking. If you take the braking energy and waste it as heat in a resistor (dynamic braking resistor) it's still called dynamic braking but, if you take the braking energy and regenerate it back into the AC supply, then it's call regenerative braking as rsdoran pointed out. Generally, if a DC drive is capable of electronic reversing (not contactor reversing) then it is also capable of regen braking.

In AC, using the motor to brake the load is also commonly called dynamic braking but, I think, the preferred, more accurate term is snubber braking since you are effectively snubbing the DC bus at some voltage higher than normal and diverting the energy to a braking resistor. Today it is also possible to buy regenerative drives which will return the braking energy to the AC supply rather than waste it. In AC, regenerative braking capacity has no connection with reversing capability as in DC.