Using Preet Speeds on a VFD

[Rick_B]

I have an Allen Bradley 160-ssc VFD that is a preset speed model. I see where parameters 61 through 68 (page 5-13 of the manual) are used to set the speeds and on page 2-20 of the manual it shows the low voltage terminal (TB3) wiring. I don't understand how the selection of a speed works? The parameter table shows the various configurations of the TB3 terminals for a specific speed but how do you activate the specific speed. I don't believe a potentiometer works with this preset speed model? Not sure how to link a pdf file of the manual - googling "allen bradley 160-ssc" will have plenty of pdf manual links

Thanks
Rick

 

[markba633csi]

HI Rick- you can use the "attach files" function to post the manual if you have the file
There is probably an enable pin you have to pull high or low to engage the speeds

 

[Rick_B]

HI Rick- you can use the "attach files" function to post the manual if you have the file
There is probably an enable pin you have to pull high or low to engage the speeds

Thanks Mark - I finally found a direct link to the ,manual

https://literature.rockwellautomation.com/idc/groups/literature/documents/um/160-um009_-en-p.pdf

Rick

 

[Ischgl99]

My reading of the manual indicates you can only use a potentiometer with the analog input model, if you have the preset speed model, you can only use discrete speeds based on your settings of the preset speeds. You would control the preset speeds through switches or a PLC. Let’s say you have a rotary switch for 3 different speeds, you would wire the output of the switch to send voltage to the TB3 inputs that correspond to that preset speed.

Let’s say you are using presets 1, 2, and 3. For preset speed 1, you would need your switch or relay sending voltage only to input TB3-1. If you wanted to use preset 2, then voltage only can be on TB3-2, but if you are using preset 3, then the switches/relays going to TB3-1 and TB3-2 must be energized.

 

[markba633csi]

Those preset speeds can be user set to any speed from 0 to 240 Hz (page 5-13)

 

[Rick_B]

OK - let's see if I got this. I would need an 8 position selector switch with 4 terminals. One for the common TB3 3 and three for the TB3 terminals 1, 2 and 4. The VFD will send a signal to the selector switch through the common. The switch will send a signal back to the VFD. Each switch position will represent some combination of TB3 terminals. For example - switch position 1 may send a signal back to the VFD TB3 terminals 1 and 2 which will activate whatever frequency is programmed for that combintion. Is that about right? How would I know the various combinations for each switch position?

Rick

 

[Ischgl99]

yes, but you only need 8 positions if you want to use all the preset speed options.

How would I know the various combinations for each switch position?

That would depend on which switch you used. The datasheet for the switch will show you the output combinations available and would determine how it got wired.

 

[markba633csi]

The manual shows you the truth table for the inputs- page 5-13

Pretty sure a closure is a 0- the inputs appear to have pull-ups- in other words they go high (1) when open

 

[Rick_B]

I saw the truth table - however all of the 8 position switches I looked at had 8 terminals. I'm not familiar with how to configure the switch with one common input and three output. Can anyone point me to a switch that would work?

Rick

 

[Rick_B]

Some more stumbling around on the internet led me to a pdf from Digitran where they described various rotary switch outputs and how they work. I found one where there truth table match the VFD parameters exactly - it was described as a binary code octal 8 position. I found some at mouser (https://www.mouser.com/c/electromec...XK1dZwv5WoEXA6r-vwSnxX-zJw7iokaVgbvU4xZ_duClj) but can't see how they mount. I need a panel mount version.
Rick