Possible to detect a motor is connected to an inverter?

[I_Automation]

Does the VFD have a DC "Moisture Control" output when the motor isn't in use?
And a Motor Current option for an analog output?


Before it's started you can check and make sure there is some motor current for warming the coils and know the motor is connected.

 

[GaryS]

If the system is designed as you describe it is a very poorly design system. All those contactors banging in and out foreword and reverse
What a mess prone to troubles.
In your case there is no sought the best way would be to have each motor on it’s own vfd. That way the vfs’ are connected all the time and each vfd controls it own motor. Controlling the speed and direction of each motor would be a simple mater.
The cost would be about the same if you consider the labor cost and hardware cost to connect all the contactors. Just 1 failure could take hours to trouble shoot and repair.
Switching contactors’ at that rate is prone to failures and you would have to derate them by about 20% due to the cycling time.
If you are drilling and taping you should be using a flux vector drive to give the best control of each motor.
And yes modern vfd’s have the ability to detect an open phase on the output or a phase loss on the input but what are you going to do if the motor contactors fail shorted and cross the lead up
Good luck with that

 

[I_Automation]

I have worked on hoists where 1 VFD powered both the X travel and Z lift motors.

It used an 8 pole contactor, 4NC, 4NO that switched between the 2 motors. The 4th contact was used for the brake.

This way the PLC had control over 3 set speeds, direction and which motor by 5 relays.

 

[GaryS]

First let me say you are entitled to your opinion
A single drive for 2 or more axes limits the operator ability to do the job and could actually endanger the operator or others for the cost of a drive Not Me
I have been doing hoist and cranes for over 30 years and have designed and built many custom systems. I have always exceeded the customer expectation and requirements. And I have been called in many times to fix bad designs by others.
Many cranes have 2 bridge motors they must run together or you get racking and the bridge jams. I have cranes with 100 ft bridge span over a 1000 ft run 100 if lift I have seen many poorly designed systems and had to come in and fix them.
I have a plant that has 6 cranes that must all run together to pick up a common load or independently as need for the job. Each crane is rated for 20 tons each.
When you pick up a common load all cranes must run exactly the same speed start and stop together or you run the risk of dropping the load and hurting somebody. I have done automatic positioning to pick and place load systems
I use radio controls for the operator to keep them at a safe distance.
Safety First. I have seen many systems where they cut corners to save cost’s then they can’t figure out why things don’t work as expected.
There are many ways to most any job it’s your choice I try and do it right and improve on job I do

 

[I_Automation]

First let me say you are entitled to your opinion

I didn't say it was my option or my design.
I have been called to work on these hoists quite a few times over the years. These particular hoists were built in Italy, and the VFD in them is a 1990 circa ABB 5HP even though the motors are 1 and 3/4HP.
Also, they are hoists, not cranes. They are self contained single frames with travel along a rack and lift to place racks in dip tanks.