Motor Start Up Sequence

Looking for an easy way to start up a bunch of motors in sequence with a delay between them without going through the task of using a bunch of timers. Logix5000.
Any help, not looking for this to be complicated.
Was thinking of using a self resetting timer to trigger a counter whose value would start a motor.
Thanks

Are these motors controlled by VFD's or contactors?

use a single TON and compare the time elapsed using a greater than instruction with a different value for each motor.

You could have a single timer and use a series of greater-than instructions, looking at the accumulated value of the timer, to start each motor.

Been there, done that. Wouldn't recommend it. Too many unforeseen circumstances to toss a fly into the ointment, unless you are looking at an incredibly simple process.

I agree with Gbeaker and Kolyur: use a single Auto-Start timer, but maybe not a Greater Than comparision. I have programmed 8 or 10 plants with an Auto-start timer, and some even with an Auto-Stop timer as well. These are plants that have a series of conveyors and other material-handling devices in a long series string.

Here is an example. Each motor has start-stop logic with a seal-in contact. I used a LIM instruction to give each motor starter 2 or 3 seconds to seal-in (depending on motor size and other delays). This example for a Raw Material Feed Elevator is the second motor in the series to start. Because most of these were low-horsepower motors, very few needed a delay, but needed to start in a sequence, and 1 at a time so as not to increase the plant power demand factor.

The first motor starts at 1 to 2 seconds for Timer T4:3. This Elevator starts at T4:3.ACC = 3 to 5 seconds. You can allow whatever delay between motors that you desire.

Using an Auto-Start timer like this with the LIM instruction works just like a momentary-contact Start pushbutton: when the start signal is done and has gone away, what remains is logic that can easily be shut down should the need arise.

What is your reason for going through this effort? If you are on a generator and you can only start so much at any one time that is one thing and you may be forced to to this.

If you are trying to reduce the demand charge from simultaneous starting that is another. Yes that demand charge can add up to serious money. What size motors are we talking about here?

Simple way to do it. Press the start button on each motor at what ever interval you choose. Downside - requires employee training.

Do motors have to start in a definite sequence ie oil pump first, cooling water second etc etc?

Dan Bentler

Why don't you want to use a bunch of timers? Timers are computer instructions, not devices. Group them into an array of timers if it helps you keep things organized. If you prefer to use object oriented programming techniques then create a UDT of type MOTOR and include a timer in the UDT. Program so that the function is obvious, not obfuscated by reusing a timer. You said you didn't want something complicated, so don't do something complicated.

Do motors have to start in a definite sequence ie oil pump first, cooling water second etc etc?

Click to expand...

Yes in my cases. Mostly they were loose fertilizer raw-materaial and final product conveyors. During plant start-up, the farthest-downstream conveyor needed to start first, followed by next-upstream, followed by 2nd upstearm, and so on up to the last one. Otherwise, material on conveyor piles up and spills in the floor because the next one downsteam has not started.

During shutdown, you have to do the sequence all over again for 10 or 15 devices, except in reverse. I had one case for a case packing system that had 100 conveyors. Try that serial startup with 100 separate timers!

Use a shift register with a timer or internal pulse as the trigger - easy.