Electrical help please

[Rink]

Any electricians or electrical engineers out there?

I need some electrical information. I want to install a Triton 3 1/4 hp router in my router table and control it with a magnetic switch. Couple questions:
1. The router specs are 110v, 15 amp. So that would be 1650 watts. But 3.25 hp at 746 watts/hp would be over 2400 watts. What am I missing?
2. I can find magnetic switches for about $40 or even less. But they are rated for 2 hp. A magnetic switch rated for 3+ hp is more like $100. Does that sound right?

Any insight greatly appreciated.

 

[MRDucks2]

You aren't missing anything, they are simply calculating HP to their advantage. Probably 3.25 HP at 22,000rpm no load. Obviously, that doesn't work in real life.

Your 2 HP switch will work fine. This router is designed to ramp up when it starts to minimize any inrush so it can run 15 & 20 amp 120 volt circuits. The 2 HP mag switch will be rated in the same range. 2 HP is realistically about the most you can get off of a 120 volt regular household circuit.

From my understanding people love this router and have had no issues with it overloading a circuit.


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[Herb G]

I tend to agree. Manufacturers often if not always over rate a motor's HP, because they think the American public is too stupid to look it up.
If it were indeed a 3.25 hp motor, it would develop so much torque that no man alive could hold & control it.
For reference, I refer you to the 6.5 HP shop vacs Sears once sold.

A true 3 HP, 120 Volt motor pulls 36 amps.
Not gonna happen in a handheld router.
:frown:


OH, you're probably good to go with the switch you want to use.

 

[Rink]

Gentlemen, thanks a lot for the info. That helps me a lot.

 

[chartle]

Yep i think there has been talk for years about what those HP ratings really mean.

 

[Rink]

I sent Triton an email and asked about the "discrepancy". We'll see how they respond.

 

[Penultimate]

The 15 amp rating does not correlate to the full load power of the motor. The 15 amp rating is based on a UL test. The 3.25 hp rating is the maximum hp developed based on a test on a dynamometer. As the motor is loaded, by increasing torque, the speed decreases. At a point in the motor curve the combination of torque and rpm equals a peak hp. Hp=torq(lbin)*rpm/63025. Then after max hp as the torque increases and the rpm decreases the hp drops. The max hp occurs about half way between no load and stall torque.
So the greater hp rating means the router will have better speed regulation at whatever torque is required to make the cut. Speed regulation means the the speed doesn't change a lot with changes in torque.
Hope this helps.


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