Electric Motor using at escalator overspeed
Electric Motor using at escalator overspeed
(OP)
Dear All,
I have one case where there is an escalator speed up while going down when loads of people on the escalator. The electric motor that has been used is 4 pole. My question, how the motor can ran overrated rpm? The motor still in the good condition.
Thank you. Hope to hear from you guys soon.
I have one case where there is an escalator speed up while going down when loads of people on the escalator. The electric motor that has been used is 4 pole. My question, how the motor can ran overrated rpm? The motor still in the good condition.
Thank you. Hope to hear from you guys soon.





RE: Electric Motor using at escalator overspeed
Possible causes:
The escalator is overloaded.
Belts are slipping.
The motor is a special design with a greater than normal slip frequency.
How much overspeed?
What is the current relative to rated current when the escalator is overhauling.
Bill
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"Why not the best?"
Jimmy Carter
RE: Electric Motor using at escalator overspeed
RE: Electric Motor using at escalator overspeed
Bill, have you seen an escalator with belts? I haven't, usually chains from g/box. That's not to say hey don't have belts but that type of load is typically not using them.
RE: Electric Motor using at escalator overspeed
RE: Electric Motor using at escalator overspeed
At synchronous speed PLUS the slip speed or slip frequency a motor will generally regenerate close to full load current.
Is this a VFD driven motor with a problem in the regeneration circuit or possibly some poor settings?
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Electric Motor using at escalator overspeed
RE: Electric Motor using at escalator overspeed
there are settings in some vfds that allow them to speed up if overrun load on them to prevent over voltage errors; might be yours is set like this (wrong for elevator).
RE: Electric Motor using at escalator overspeed
RE: Electric Motor using at escalator overspeed
Check your contactor and wiring for loose or corroded connections. Evidence of heat will be an indication. The motor may appear good, but there may be a problem with the rotor. A growler test may be indicated.
Mechanical. There can't be any mechanical slippage, right? I have seen issues where a coupling was slipping on a shaft and throwing the machine timing out. Couldn't happen, right? I had to paint a line across the coupling to demonstrate to the mechanical guys that what couldn't happen was happening.
Do you have a spare, good motor? Change out the motor. If the problem goes away it is a motor issue. If not, then check the supply (unbalanced currents may or may not be an indicator. If the supply looks good then look for a mechanical issue.
Bill
--------------------
"Why not the best?"
Jimmy Carter