Emergency Shutdown Switch per IEC 60947-5-1

[farmer2]

I am looking for a push-button operated emergency shutdown switch for use at up to 400 amps, 12V DC and up to 200 amps, 24V DC for winches per an EN standard. These are full-load amps for the winches. At stall torque the motor may draw 50% higher current which I assume should be the max. switch rating (600 amps 12v, 300 amps 24v).

The IEC spec is called out in the EN winch standard and also says "switch shall be of the self-latching type and shall have positive (direct) opening action. Actuator shall be of the palm or mushroom head type, colored red, with the background around the actuator colored yellow"

Are the above requirements specified in the IEC spec and does anyone know any manufacturerers of such a switch? I do not have a copy of the spec.

Thanks,

 

[ScottyUK]

The conventional way to do this would be to use an emergency stop button to the IEC standard in the control circuit of a contactor. When the switch is pressed a contact opens and cuts power to the contactor coil, cutting power to the main circuit. You won't find an IEC 60947 switch capable of breaking that current directly.

There are loads of manufacturers for the emergency stop switches themselves. In roughly alphabetical order: ABB, Allen Bradley, Bartec, Craig & Derricott, Moeller, Siemens, Telemecanique... too many to keep going! The contactor would probably be from someone like Hubbell or the like specialising in heavy current low voltage DC applications. The winch presumably has a contactor, so maybe you can interface to this?


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If we learn from our mistakes I'm getting a great education!

 

[dpc]

Agree with Scotty. Even though it is only 12 Vdc, breaking 400A dc is non-trivial. I'd use some type of normally-closed E-stop pushbutton to drop out the contactor that is running the motor.

 

[farmer2]

Thanks ScottyUK and dpc,
We currently have two types of emergency shutdowns. One is as you describe: it is a NC solenoid (separate from the winch operating solenoids) in the + cable and a toggle switch is used to open the solenoid to shutdown power to the main solenoid. The problem is with this requirement:

"switch shall be of the self-latching type and shall have positive (direct) opening action." It has neither of these features.

The other shutdown switch we offer is a manual switch which directly opens and closes the contacts which are rated for even higher current than needed, but this switch does not meet the requirement. It has positive opening action, but cannot be operated by a remote push button switch.

Is there another interpretation of the requirement?

 

[ScottyUK]

The latching requirement relates to the emergency stop switch itself. The circuit it controls does not need to be a latching type, but the contactor should de-energise the load when power to the coil is removed. This is the standard configuration for countless thousands of E-stop installations.

This link shows a typical example.

http://www.klocknermoeller.com/klockner.moeller/klockner.moeller.safety.products.htm

Electrically the switch is closed when the switch is not pressed, and open when the switch is pressed. The switch mechanically latches when pressed.



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If we learn from our mistakes I'm getting a great education!

 

[farmer2]

Thanks, ScottyUK.

What you say makes sense. Looks like we would want to use the stay-put, either pull to release or the button release. If I understand the spring return, it is momentary, so the stop solenoid would not stay open. Would the pull to release be the best choice?

This looks like the solution that would be used in conjunction with the push button hold-to-run remote control switch.

 

[ScottyUK]

Hi Farmer2,

I tend to use the stay-put, twist-to-reset style of push button E-stop, but there are many variants for different applications and operational conditions. I've used the key reset type in a different industry to the one I work in now so that a line can't be restarted from a E-stop condition except by a supervisor or engineer.

I'm not 100% certain I understand how your winch switches on and off. Most contactors have one coil which energises and closes the contacts, and opens the contacts when the coil is de-energised. They're pretty simple to add an E-stop function. Does this scheme have separate solenoids to energise and de-energise the motor? That will be a little more complicated. Have you got an internal wiring diagram for this winch?


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If we learn from our mistakes I'm getting a great education!

 

[farmer2]

Thanks, ScottyUK. There are 2 solenoids to operate the motor-one solenoid to run clockwise and one to run CCW. They are operated by a two-push button (hold to run) remote pendant. Between the battery and the solenoid assy is the emergency shutdown solenoid, which is operated by a rocker switch in the vehicle cab.

Looks like the location of the E-stop switch should be between the rocker switch and the shutdown solenoid. The E-stop would be NC. The emergency shutdown solenoid is NO (my original post said NC which is incorrect).

Do you agree?

 

[ScottyUK]

If the shutdown solenoid behaves as a "dead man's handle" so that if it de-energises for any reason then the winch halts, and the shutdown solenoid over-rides the run CW / run CCW solenoids then that seems a reasonable place to connect the E-stop.

Purely for my own curiousity, how do these solenoids control the winch? Are they mechanically locking the drum?


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If we learn from our mistakes I'm getting a great education!

 

[farmer2]

The solenoids control the motor rotation direction. The IN solenoid runs the winch in, the OUT solenoid runs the winch out. If power is lost for any reason, a brake mechanically stops movement.

If the E-stop is between the rocker switch and the shutdown solenoid, then if it de-energises, the winch will stop because the shutdown solenoid will open.

Thanks for your help.