AB140m

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ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
Cow said:
I'm told it's affects the devices trying to read the cows ear tags. The VFD and output wiring are basically like a giant FM antenna that cause interference issues. The closer the VFD and shorter the motor leads, the less interference.

Over here, they read the ear tags on the milking carousels for individual cow statistics, they also use the tags to automatically open and close sort gates to sort cows into certain pens, they are used for body condition cameras, and on and on. In the freestall barns, they have activity sensors to monitor for cows in heat for breeding purposes and the employees also use hand scanning RFID wands for identifying and working with the animals directly.

As you can tell, they use the RFID tags for tracking almost everything.

If the farm you're at doesn't use RFID ear tags, or isn't planning on doing this anytime in the future, then it's not a problem.

https://www.valleyvet.com/ct_detail.html?pgguid=C2ECD51C-D599-4BB1-8B06-E73CF9633B99.
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They were using one of these the last time I was there.

They don’t track the individual production per cow but do know when that average drops on at least a daily basis.

They were hoping to save some up front costs and add a VFD per group vs individual fans. I’m thinking 2000 feet of VFD cable alone might negate that thought.

On to plan B.
 
P

paulengr

Senior Member
ptonsparky said:
They were using one of these the last time I was there.

They don’t track the individual production per cow but do know when that average drops on at least a daily basis.

They were hoping to save some up front costs and add a VFD per group vs individual fans. I’m thinking 2000 feet of VFD cable alone might negate that thought.

On to plan B.
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VFD cable is useful to roughly double the distance before reflected wave is an issue. For example on Allen Bradley Powerflex drives the maximum line length goes from 50 to 80 feet. That's it. Even then it's a joke. #14 THHN which has the thinnest insulation is rated 600 V but passes a minimum of 2200 V by Codes. Actual testing by NEMA shows it works to 2800+ regardless of brand. XHHW which is thicker goes to 3200 V. VFD cable goes beyond these ratings but let's get back to the motor. Very old motors without phase papers are limited to 1000 V. Inverter duty motors with phase paper built to beyond Code specs hit 1700-1800 V peak ratings. So if THHN is rated to 2200 and tests to over 2800, can a VFD cable manufacturer please explain what VFD cable does other than line their pockets?

The issue is protecting the motor. The motor has the tighter limits. Protect the motor and the cable doesn't matter. VFD cable is a ripoff.

AB sells VFD cable so they push it but most dealers do not bother to read their own manuals. At 2000 feet it's useless. So are dv/dt filters. Only a sinus filter will handle that distance. With that filter, VFD cable does nothing but help improve the profit margin.

A ship loading facility I visited at a port used all AB equipment. We rebuilt the gear box but i was sent out because we had fluting in the gear box (???) Its not even a close coupled motor like a C face buf its an all metal coupling. As per the AB distributor they spent obscene amounts of money pulling out THHN and installing VFD cable for their 500-1000 foot runs. Motors still failed in 6 months. The gear box failed in 18 months. Transients were not just random but 2 KHz (drive carrier frequency). Ringing transients were stupidly high, over 2 kV, on the phase conductors. Well at least they won't have to rerun cable! We could have dropped TCI filters in their huge drive cabinets for less than the cost of the cable itself.

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