Motor emergency stop botton position?
Motor emergency stop botton position?
(OP)
Hi,
I need your comments on which alternative is better for stoping a 100 kw motor driving a ventilation fan in an underground mine when you push the e-stop botton next to the fan.
The motor is drive by a 100 kw VSD. The manufacture of the VSD is offering a digital input in the equipment to conect the e-stop botton, so in case someone push it the output signal to the IGBT´s stop and the motor stop. The VSD keep energize under this configuration.
The configuration I have seen in other mine sites is that the e-stop botton de-energize the contactor that supply the power to the VSD, so in case someone push the botton the whole system is shut down, VSD and motor. I think this configuration is better since is not subject to issues with the digital input and electronic cards in the VSD.
Please comment.
Thanks.
I need your comments on which alternative is better for stoping a 100 kw motor driving a ventilation fan in an underground mine when you push the e-stop botton next to the fan.
The motor is drive by a 100 kw VSD. The manufacture of the VSD is offering a digital input in the equipment to conect the e-stop botton, so in case someone push it the output signal to the IGBT´s stop and the motor stop. The VSD keep energize under this configuration.
The configuration I have seen in other mine sites is that the e-stop botton de-energize the contactor that supply the power to the VSD, so in case someone push the botton the whole system is shut down, VSD and motor. I think this configuration is better since is not subject to issues with the digital input and electronic cards in the VSD.
Please comment.
Thanks.





RE: Motor emergency stop botton position?
RE: Motor emergency stop botton position?
RE: Motor emergency stop botton position?
I've always felt that it was bad form to rely on a digital input to do your emergency stopping, so if it were me, I'd insist on a hard-wired e-stop connection to the contactor.
RE: Motor emergency stop botton position?
RE: Motor emergency stop botton position?
A word of warning if you simply drop out the contactors on the power into the VSD: The bus capacitors in the drive store a lot of energy, usually more than the kinetic energy of a motor rotor. If the drive does not automatically disable itself on loss of input power, the motor can be driven for quite a while after power is removed.
Increasingly, I'm seeing regulations that require that an e-stop drop out control power to the "gate driver" circuits inside the drive that allow the power transistors to be turned on. Some of these permit the use of silicon in the path, but none permit the use of software to do this.
Curt Wilson
Delta Tau Data Systems
RE: Motor emergency stop botton position?
But droping power on input side was never my first way to do it. It seems like the manufacturer's of drives draws it in their docs to pull power on the input feed to the drive, I think this sets the drive up for premature failure.
I think the best way is estop contactor on the output of the drive and disable the enable on the drive during estop. Of course during ramp up or down make sure that the contactor stays pulled in during this stopping and starting for a normal stop/start. Just seen it both ways, not sure which way is code sanctioned and dont think they do point out this in references.
RE: Motor emergency stop botton position?
The gate drive inhibit circuits have been through a lot of testing, in some circumstances sufficient to meet Cat 4 of the EN954 machinery safety standard - not an easy requirement to pass, so they're worthy of consideration. Personally I still like to see a physical airgap in the power circuit, so an input contactor is still my initial solution but I am increasingly attracted by the gate inhibits when used with a safety relay such as a Pilz PNOZ or similar.
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