Fuse for an AC motor
Fuse for an AC motor
(OP)
this is probably a dumb question, but...
For an AC 120v 60hz, single phase motor (which is no longer being made); the tag on the 3M127B Dayton motor says 1.4 amp.
I'm assuming that means operating amperage at 112 in lbs max torque.
Motor is non-reversible.
So...what would be the rating for a fuse to protect the motor from overload?
Thanks
For an AC 120v 60hz, single phase motor (which is no longer being made); the tag on the 3M127B Dayton motor says 1.4 amp.
I'm assuming that means operating amperage at 112 in lbs max torque.
Motor is non-reversible.
So...what would be the rating for a fuse to protect the motor from overload?
Thanks





RE: Fuse for an AC motor
If the motor is not self protected, it's better to use an "overload relay" or a "manual motor starter" with one built-in. They are much better at protecting against overloads than fuses are, plus they are resettable, unlike fuses.
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RE: Fuse for an AC motor
RE: Fuse for an AC motor
Explain in nice simple words how that would provide any form of overload protection. The motor could draw 5A indefinitely, or at least until it caught fire, which seems to defeat the purpose of overload protection. Following your reasoning, why not take it a step further and replace the fuse with a 1" diameter bolt. That gets around the problem of blowing the fuse entirely.
I hope you don't design, install, or maintain electrical installations for a living, but if you do please let us know where so we can keep well away from them.
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If we learn from our mistakes I'm getting a great education!
RE: Fuse for an AC motor
Part Number 2510FF1 (Square D)
Description : Fractional Horsepower Manual Starter , Non-Reversing, 16A, 1HP(AC), 1-Phase, 1-Pole, Provides overload protection as well as manual ON/OFF control for small motors in a variety of industrial and commerical installations., Type: F, Operator Type: Toggle, Overload Type: Thermal - Melting Alloy, Reset Method: Manual, Thermal Units Required: 1, Single Unit Gray Flush Plate, Mounting Type: Flush, Depth: 1.44 Inches, Height: 4.50 Inches, Width: 2.75 Inches, 600VAC/250VDC
Price $52.00
RE: Fuse for an AC motor
RE: Fuse for an AC motor
#2 As for nice simple explanation that you requested,it is called a Class R fuse. Just do the math, and pick the right one.
RE: Fuse for an AC motor
Giving irresponsible and dangerous advice is nothing to be proud of, anonymous or not. A 5A fuse does not provide any overload protection whatsoever for the motor; your advice is that of an idiot. No offence.
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If we learn from our mistakes I'm getting a great education!
RE: Fuse for an AC motor
Dual element fuses do provide separate overload and short circuit protection. For a 1.4A motor a 2A or 3A dual element class J fuse should work. Start with low and up it if required until the motor starts normally.
RE: Fuse for an AC motor
Ditto. As I read the code, the OL device should be about 115%. With Dual element, no problem. Fast blow fuses may need to go up to 125%.
RE: Fuse for an AC motor
sorry but i don't know, i do thank you all,
Best Wishes,
devojka = (girl)
"women make such excellent scientists and engineers-because of their passion for learning and will-power to succeed..."
RE: Fuse for an AC motor
In the first post, the motor full load current is given as 1.4 Amps.
All percentages are percentage of full load amps.
A 5 amp fuse will give some protection to the rest of the installation after the motor burns out. A bolt won't, but these circuits are normally protected at 15 amps in the panel. When the motor burns out, the 15 amp breaker in the panel will race with the 5 amp fuse. Either one may win, or it may be a tie. (Both interrupt)
If you go with dual element fuses, the man who sells them to you may have a sizing chart for motor protection. If not, check the fuse manufacturers web site for the size.
I remember one such chart from many years ago when I was he head electrician in a Western Canadian lumber mill.
The book had pages of fuse sizes correlated to motor full load current. At the bottom of each page was a little notice:
For light duty use one size smaller.
For normal duty use the size listed.
For heavy duty use one size larger.
Then, rubber stamped by hand near the bottom of each page,
For sawmill duty in Western Canadian lumber mills, use two sizes larger. We were brutal to the motors but we were very very fast changing out burned out motors. (Practice makes perfect.)
Bill
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"Why not the best?"
Jimmy Carter
RE: Fuse for an AC motor
***** you are Sunshine.
devojka
"women make such excellent scientists and engineers-because of their passion for learning and will-power to succeed..."