[lens42]

I'm almost done with an enclosure for my 770, and realize I probably need another estop outside. Since the 770 says it needs 20A service, I figured I needed a 20A estop switch since all of the machine power goes through that switch (yes?). After not being able to find one rated for 20A, I looked inside the control cabinet and see the estop switch Tormach uses is only rated for 10A. I guess 10A must be OK, but this seems to not add up. Can anyone clarify?

[Al_The_Man]

I am not familiar with the 770 but the general rule is a E-stop string is carried out with low voltage, 24vdc being popular, the end result is a large relay or in the case of 20amps, a contactor should be used to drop out any significant power.
This is the industry way of doing it. Unfortunately most hobby machines do not conform to this method.
Al.

[popspipes]

I have an 1100 and the power is dropped out with a relay, maybe an amp or so thru the switch.

[lens42]

Thanks. That makes a lot more sense.


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[tmarks11]

I am not familiar with the 770 but the general rule is a E-stop string is carried out with low voltage, 24vdc being popular,.

The estop has 120V running through it (not 24V), and the only load powered off it is the machine control board and the C1 & C2 contactors. It is protected by a 2 amp fuse. So... much less than 1 amp.

Other than that, Al is right and all the large loads in the machine are powered directly when the contactor (C1 or C2) contacts shut. The stepper motors and the VFD are all powered through contacts on the contactor, with power coming from 120V (VFD) and the 120V/40V transformer and DC bus board.

[kstrauss]

I have an 1100 and the power is dropped out with a relay, maybe an amp or so thru the switch.

I have a 770 and, like the 1100, the power is controlled by the eStop switch and relay. Certainly no need for a 20amp switch!

[TXFred]

It it helps, I used this switch to add a second E-Stop to my Series 2.
http://www.automationtechnologiesinc.../e-stop-switch