Overloads needed for jib crane?
Overloads needed for jib crane?
(OP)
We're installing a rotating jib crane. On the crane is a 3 ton hoist that utilizes a 2hp, 3ph, 230VAC motor. The hoist is on a motorized trolly that has a 1/4hp, 3ph, 230VAC motor. The crane uses an pendant control with 4 buttons(up, down, left and right). The crane was manufactured by Coffing. The crane was shipped to us as an "assemble on site" package. It has only one place to supply power and one nameplate.
Does the feed to this crane need motor overloads? I can't see any overload devices on the equipment or in the manufacturers prints. Am I being too careful? Should the crane be considered "industrial equipment" that has to meet NFPA 79 at it's place of origin?
Here's what I'm thinking I need: disconnect, short circuit and overcurrent protection for the branch circuit that will feed the crane. Size the circuit slightly larger than that of the required nameplate current data. Am I right? ...or do I need overloads.
Does the feed to this crane need motor overloads? I can't see any overload devices on the equipment or in the manufacturers prints. Am I being too careful? Should the crane be considered "industrial equipment" that has to meet NFPA 79 at it's place of origin?
Here's what I'm thinking I need: disconnect, short circuit and overcurrent protection for the branch circuit that will feed the crane. Size the circuit slightly larger than that of the required nameplate current data. Am I right? ...or do I need overloads.





RE: Overloads needed for jib crane?
Keith Cress
kcress - http://www.flaminsystems.com
RE: Overloads needed for jib crane?
But to speak to your question directly, no you cannot just put in an OL relay to feed a circuit like this. You will need separate OL relays for each motor. No exception.
RE: Overloads needed for jib crane?
It's one of these: http://www.coffinghoists.com/ecpage.html
Model ECMT-6010-15
You really think I have to put seperate(hoist/trolley) external overloads on that thing?
RE: Overloads needed for jib crane?
BK
RE: Overloads needed for jib crane?
RE: Overloads needed for jib crane?
The factory will not say, "you don't need overloads", but I've never seen them used on these. Logically you don't need them, code wise, I believe you do unless sub 1hp motors don't, I don't recall off-hand.
Now that I look back and see you have a 2HP unit I would probably include overload protection.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Overloads needed for jib crane?
I would do this in a hoist because you don't want the motor to cut out with a load hanging on the jib.
The more modern option would be to use a solid state OL relay, The last one I used had alarm contacts but I can't remember if they could be set at say 95% of full load.
RE: Overloads needed for jib crane?
Per our interpretation of the specifications we are not required to install thermal protection on the hoist, this is optional equipment that has to be specified by the users depending upon local codes in the area of the hoist installation and use. If you need such devices we can provide them, with an additional charge. If you have any questions please let me know.
Joe Schmoe(name changed for reprinting purposes)
Applications Engineer
Coffing Hoists
PH# 800-694-****
Fax# 800-374-****"
RE: Overloads needed for jib crane?
Here is the wiring diagram; no OL shown.
RE: Overloads needed for jib crane?
Another motor application that doesn't have overloads is a fire water pump.
Roy
RE: Overloads needed for jib crane?
While it may not be technically "right", there are millions of hoists being used this way every day. *I* wouldn't sweat it, but I have many more serious legacy problems to deal with.
IMHO, if you get nailed by an inspector on this fine a point, you are damn lucky to have such a clean facility!
RE: Overloads needed for jib crane?
RE: Overloads needed for jib crane?
Is duty cycle a determining factor for need? Is this in the NEC?
RE: Overloads needed for jib crane?
I also would think that if the motor had built-in thermal protection, it would be shown on the wiring diagram or at least stated in the manual. But then again, that may be a ploy to get people to call their service department and incur fees.