Design Idea..

[zai_jnr]

Hi everyone,

i wonder how to design for motor status:

- how to design to check motor speed (speed can monitor in PLC)
that mean, any increment of speed we can see the value of speeding ( let say we monitor in touchscreen or SCADA).
-to check status motor, OFF or ON condition ? Normally i using magnetic contact ON status to show motor ON or OFF condition. But i think this is the wrong practice.

-what other information we need to monitor for motor, in case all information we need include in our design touchscreen or SCADA system.. ( i think now : status ON/OFF, Fault, how long motor running for next maintenance,)

Any idea from senior or junior members?

 

[seppoalanen]

With VFD in fildbus:
- Power, Current, Torque, Speed, Voltage, DC-Voltage, Temperature, VFD Fault-ID/Description from Text-List, etc.

 

[Ken Moore]

We often use closed loop control for VFD's, we have many pumps were we run them at a set RPM, these pumps have RPM feedback via a prox. switch and a 60 tooth sprocket on the pump shaft. We also, current, and "running" signals from the drive.

For single speed motors, we use the aux. contacts to show the starter is "pulled in" and current sensors to show that the motor has a load, and the coupling is not broken.

 

[Tom Jenkins]

You don't actually say you are using a VFD. If so, the run contact from the VFD and the speed feed back signal from the VFD are sufficient for most conditions.

If you need absolute confirmation that the motor is following the command you will need to add a tachometer. Most common is using a prox switch or similar device to monitor a key or other feature on the motor shaft. That will verify rotation in case of a motor stall etc. Red Lion among others makes some excellent devices for doing this.

 

[dogleg43]

You don't actually say you are using a VFD. If so, the run contact from the VFD and the speed feed back signal from the VFD are sufficient for most conditions.

If you need absolute confirmation that the motor is following the command you will need to add a tachometer. Most common is using a prox switch or similar device to monitor a key or other feature on the motor shaft. That will verify rotation in case of a motor stall etc. Red Lion among others makes some excellent devices for doing this.

Not trying to be picky, but the prox switch/motion sensor probably should be sensing motion of the shaft of the load (conveyor, fan, etc.). Sometimes the couplings break or come loose connecting the motor to the load.

 

[Tom Jenkins]

Not trying to be picky, but the prox switch/motion sensor probably should be sensing motion of the shaft of the load (conveyor, fan, etc.). Sometimes the couplings break or come loose connecting the motor to the load.

You're absolutely right. He asked about motor rotation and I was sucked right in!

 

[zai_jnr]

ooo..i see...using VFD anything can be done rite??
before this I'm only using VFD just for speeding changing, but never collect any data from VFD to PLC programming...
May i request any member who have any sample to show how to pickup data from VFD to PLC?

 

[manmeetvirdi]

As seppoalanen said
You can read all this if you are using bus to communicate with VFD.Using profibus with MM440 you can display power consumption too. ON/OFF/Fault/Warning/Motor overload/Inverter/Overload etc
Even fault number and then remedy of the fault occurred !!

 

[JesperMP]

If it is just a normal direct start (no VFD), then a simple yet very informative information is the motor load, rather than the motor speed that does not vary much.

There are cost-effective current transformers with 4-20mA output, and analog inputs doesnt cost much, and you dont have to lay cables and install sensors outside the control cabinet.

 

[zai_jnr]

As seppoalanen said
You can read all this if you are using bus to communicate with VFD.Using profibus with MM440 you can display power consumption too. ON/OFF/Fault/Warning/Motor overload/Inverter/Overload etc
Even fault number and then remedy of the fault occurred !!

wow!! VFD actually very great function, not only can changing speed of motor..but can feedback a lot of info to PLC for monitoring status.. Erm..that mean, i need to more study about VFD function and profibus function...hu hu hu

Using profibus with MM440 you can display power consumption too.

what the specific brand for MM440?

 

[zai_jnr]

If it is just a normal direct start (no VFD), then a simple yet very informative information is the motor load, rather than the motor speed that does not vary much.

There are cost-effective current transformers with 4-20mA output, and analog inputs doesnt cost much, and you dont have to lay cables and install sensors outside the control cabinet.

Could you more elaborate for this design? Still blur with this idea...