Possible Safety Power Switch for C Series Headstocks

[everettdavis]

I am always looking for a replacement switch candidate and came across this one in a catalog and found it on Amazon for $11.40 free shipping.

Superior Electric SW7C Aftermarket On-Off Toggle Switch (Optional Lock) 24/12A - 125/250V

I haven't ordered one yet, but wondering if anyone was familiar with it yet. It offers the safety switch off paddle, and a removable lock

Thoughts?

Everett

superior electric sw7c 4.jpg (88.74 KiB) Viewed 15028 times

[mountainbreeze]

That looks interesting and I may give it a try. My current switch (which is a replacement of the original) is starting to fail in a similar manner to the last one in that when I toggle it off, the motor continues to run. Very unsafe.

[dusty]

It looks good but I will most probably not incorporate one. I replaced my original switch several years ago after I arced two of the connector tabs. When I did that, I purchased a replacement and a couple spares which I still have. Indications are that I now have a life time supply.

It does look good though because it offers the safety switch function. I wonder, though, is this the same sort of switch with some sort of flapper that been incorporated.

[JPG]

Is there a HP rating on the back side?

Looking on line, it appears there is NO HP rating and it has a 12A(24vdc) rating.

I fear it is not robust enough for motor loads and could be short lived. However the sales blurb infers use on tablesaws and other power tools.

[dusty]

Mark V on-off switch (substitute).PNG (153.46 KiB) Viewed 14964 times

This is what I find in the Superior catalog (yes-no HP rating).

But does this not indicate that the switch will handle 24 amps when operated at 125 vac (OR 12 amps when operated at 250 vac).

I know from practical measurements that except for the very momentary startup current my Mark V motor draws less than 15amps at 125vac.

Do we need to know HP ratings to be able to select a suitable switch? What is the HP rating of the switch that I would get if I bought one from Shopsmith.

I will confirm, momentarily, whether or not the switches I got from Shopsmith are so rated. I don't believe they are.

Well, I failed on that exercise. Neither the switch nor the associated paper work indicate HP rating. However, I did find that the three switches I have are rated at 24/12A 125/250V-. Interpret that as you will.

[JPG]

Mark V on-off switch (substitute).PNGThis is what I find in the Superior catalog (yes-no HP rating).

But does this not indicate that the switch will handle 24 amps when operated at 125 vac (OR 12 amps when operated at 250 vac).

I know from practical measurements that except for the very momentary startup current my Mark V motor draws less than 15amps at 125vac.

I think it 'says' 24A @ 125V AND 12A @ 250V

P.S. THE HP RATING IS AN INDICATOR OF ABILITY TO HANDLE ARCING DUE TO INDUCTIVE LOADS(motors).

[dusty]

Mark V on-off switch (substitute).PNGThis is what I find in the Superior catalog (yes-no HP rating).

But does this not indicate that the switch will handle 24 amps when operated at 125 vac (OR 12 amps when operated at 250 vac).

I know from practical measurements that except for the very momentary startup current my Mark V motor draws less than 15amps at 125vac.

I think it 'says' 24A @ 125V AND 12A @ 250V

P.S. THE HP RATING IS AN INDICATOR OF ABILITY TO HANDLE ARCING DUE TO INDUCTIVE LOADS(motors).

Arcing do to "inductive load" OR arcing due to "inrush currents"?

[dusty]

Mark V on-off switch (substitute).PNGThis is what I find in the Superior catalog (yes-no HP rating).

But does this not indicate that the switch will handle 24 amps when operated at 125 vac (OR 12 amps when operated at 250 vac).

I know from practical measurements that except for the very momentary startup current my Mark V motor draws less than 15amps at 125vac.

I think it 'says' 24A @ 125V AND 12A @ 250V

P.S. THE HP RATING IS AN INDICATOR OF ABILITY TO HANDLE ARCING DUE TO INDUCTIVE LOADS(motors).

Arcing do to "inductive load" OR arcing due to "inrush currents"? I think we are saying the same thing using lay terms vs EE terms.

As a side note: 15A at 125VAC with 75% efficiency equals 1.89HP. Is this the HP rating that we are discussing?

[JPG]

Mark V on-off switch (substitute).PNGThis is what I find in the Superior catalog (yes-no HP rating).

But does this not indicate that the switch will handle 24 amps when operated at 125 vac (OR 12 amps when operated at 250 vac).

I know from practical measurements that except for the very momentary startup current my Mark V motor draws less than 15amps at 125vac.

I think it 'says' 24A @ 125V AND 12A @ 250V

P.S. THE HP RATING IS AN INDICATOR OF ABILITY TO HANDLE ARCING DUE TO INDUCTIVE LOADS(motors).

Arcing do to "inductive load" OR arcing due to "inrush currents"?

The 'inductive' load will result in slower current increase at startup, however that current level will be high due to low impedance when the motor is NOT rotating. Only that higher current will affect
the contact current stress.

However at turn off, the collapsing field in the motor will become a voltage generator that stresses the contacts by creating condition for severe arcing that does not occur at contact closing.

As for HP rating of the switch, I am not sure that the calculations suggested above are sufficient to define a rating.

I 'interpret' the SS switch rating as encouraging for 'sw7c' use.