Electro-hydraulic actuator

[HenrikOlsson]

Hi Don,
Actually, lets say the situation is the same as before, current flowing from left to right thru the motor. This time, in order to stop the motor, you switch the right hand side contact to its upper position. While the right hand side contact is open can you show me path for the current to circulate?

If you connect a diode from each side of the motor to the positive rail as well there will be a path.

The difference between a normal diode and a "fast switching diode" is not the turn-on-time, it's the turn-off-time or reverese recovery time as it's called.
When the diode is forward biased and conducting current from anode to cathode its PN junction is charged. When the voltage across the diode is reversed this charge needs to be depleted before the diode is actually blocking the current. This means that the diode is actually conducting current backwards for a (very) short time before it starts to block it.

/Henrik.

[Steve_88]

I have a few 1500 watt, 20 + vdc unidirectional transient voltage suppressors around. Sounds like these would do nicely?
Also, I'm having little luck finding suitable relays. I was hoping to stay away from the large can types. It seems most automotive types listed at Newark, Mouser, Digikey top out 40 to 50 amps.
I was hoping for a bit of a buffer, the actuator tops out at 50 maps. For my application I'm at the low end of the pressure range, it will be typically drawing around 20 amps.
Thanks

[Normnet]

I have a few 1500 watt, 20 + vdc unidirectional transient voltage suppressors around. Sounds like these would do nicely?
Also, I'm having little luck finding suitable relays. I was hoping to stay away from the large can types. It seems most automotive types listed at Newark, Mouser, Digikey top out 40 to 50 amps.
I was hoping for a bit of a buffer, the actuator tops out at 50 maps. For my application I'm at the low end of the pressure range, it will be typically drawing around 20 amps.
Thanks

See Grainger for contactors.


Norm