A PLC and a washing machine

[REHJ]

Yea what BobB said! Omron has some Great options but after having cut my teeth on Omron PLCs I have since moved on to the Direct Logic PLCs. They are just a better option for me after having moved to a much smaller plant. The cost is great! Chances are if you have to buy one thing for the AB system you can stop buy the complete system software and all from Direct Logic and still save money. The DL06 would do what you want giving you the option to control the drive with either an additon analog output or just using the selected speeds option on the inverter. (chances are this is all you would need to do).

 

[mgprim]

controlling the VFD

If I want to take advantage of the digital input on my VFD, what SLC 500 module do I need to get? Is it the 1747-OA16 (triac module)?

 

[OkiePC]

What is the exact part number of the VFD?

In most cases a relay output card (1746-OW16) will work. You simply wire the VFD signal power to the common terminal(s) of the relay card, and wire the outputs of the card back to the input terminals of the drive.

In your ladder logic, when you place a "1" in the output data file for the card point(s), the corresponding relay will close and complete the circuit.

If the drive using 120vac inputs, or even if it only uses 5vdc inputs a relay card will work.

Of course a relay card will have a shorter life span than a solid state output card, so be aware of that fact, especially if you're buying used parts from ebay.

I also think that a washing machine is an excellent training example. No one will be intimidated by understanding how it is supposed to work, and most people have thought of things they would like to customize in their own home units. Your machine will give the trainees a perfect opportunity to learn how to do this.

Paul

 

[mgprim]

VFD part number

The VFD that I have is a Leeson Model:174276.00. It requires an input of 208/240 Vac 3 phase and will power a 1hp 208/240 V 3ph motor. The VFD has separate terminals for voltage (0-10vdc) and current(4-20ma) inputs. It has a digital input reference terminal and three specialty fuction terminals.

 

[OkiePC]

http://www.leeson.com/TechnicalInformation/pdf/manual_smplus.pdf

According to that manual, you have a 1HP drive for use with 3 phase 208/240 VAC input. Make sure that suits your application first and foremost.

On page 16, it says that the control wiring digital inputs can use an external source of 12-28vdc, so you could use a 24vdc output card, however, I did not see (in my brief scan of the manual) a place to connect the DC common from the output card to the drive. Usually it is necessary to do that to ensure that the drive inputs and the external supply have the same reference voltage. For that reason, I would still recommend using a relay card and use the power source provided by the drive terminal 11.

 

[marzsit]

Hi yall,
I am very new at the PLC. I am working on a project that involves controlling a commercial front loading washing machine with a PLC. I have been looking at the Allen Bradley SLC 500 series, and I was wondering what modules do I need to get.

The components in the machine that need to be controlled are the following:

3 water valves (220V ac)
1 drain value (220V ac)
1 pressure switch
1 door lock solenoid (220V ac)
1 door switch
1 power incidator light (220V ac)
1 Variable Frequency Drive (220V ac 3phase)
1 1HP 230\460 V ac 3 ph motor

I also have an Allen Bradley PanelView 600 with RS-232 and DEVICENET, in which the user would use to change cycle settings. The Variable Frequency Drive has analog voltage and current inputs to change the direction and speed of the motor.
My plans are to use the PLC and operator panel to drive the washing machine. I would like the PLC to control the speed and direction of the motor by suppling the VFD with the proper voltage or current, and for the PLC to react when the door is open and when the water level is not high enough. Any help or suggestions would be GREATLY APPRECIATED!!!

Thanks!

won't you also need a water level switch, or a high limit?

 

[keithkyll]

...On page 16, it says that the control wiring digital inputs can use an external source of 12-28vdc, so you could use a 24vdc output card, however, I did not see (in my brief scan of the manual) a place to connect the DC common from the output card to the drive...

Looks like contact closure to me. Use a relay output card, common to pin 2. From page 15 of the manual:

10.6 SPEED REFERENCE SELECTION
If an analog speed reference input is used to control the drive speed, terminal TB-13A, 13B,
or 13C (Parameter 10, 11, or 12) may be programmed as the input select for the desired
analog input signal. When that TB-13 terminal is then closed to TB-2, the drive will follow the selected
analog speed reference input.