"DaveC" wrote in message
...
Looking to provide switching for 1-phase, 220 AC, 1/2 hp motor that
doesn't
include use of a contactor. I appreciate the need for precise
current limit
(LRA) that a branch breaker can't provide.

So, I choose to not have a contactor but instead, this, which
provides the
power-fail protection:

http://www.amazon.com/Woodstock-D4160-110-Volt-Paddle-
Switch/dp/B005W17HYY/ref=pd_sim_hi_1/191-4569239-2528519

This has a relay (rated 1/2 hp) that drops out on power fail, and
has
external connections for additional e-stop mushroom switch. But no
provision
for motor protection.

Would 2 precisely-matched (ie, to the 1/4 amp), slow-blow HRC fuses
be
sufficient to protect this motor?

Thanks.

Why do you need two fuses for a single-phase motor?

Do you know the motor's actual i-squared-t overcurrent limit
requirement?

http://www.copleycontrols.com/motion/pdf/IsqT.pdf

When I ran a lab at Mitre an engineer kept asking me to buy him more
and more Polaroid film for his scope camera. I finally asked him why
and found that he was trying to discover the principles of how a fuse
blows. He looked really sheepish and subdued when I handed him a
Littelfuse pamphlet of current vs time curves.
http://www.littelfuse.com/~/media/fi...ofuseology.pdf

jsw