Has anyone installed or specified these filters in VFD applications?
http://www.mtecorp.com/products/dv-sentry-dvdt-filters/
http://www.mtecorp.com/products/dv-sentry-dvdt-filters/
MTE DVDT Filter
- Thread starter nhee2
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I'd be interested to know what it is other than passive components.
Yes. I am also wondering makes it any different than a load side reactor with a better marketing brochure.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
It's a reactor + a capacitor and resistor making it an LRC low pass filter. I use them all the time when the lead length from motor to drive exceeds the maximum recommendation of the drive mfr. By having the load reactor it provides the drive output protection but the RC components on the other side of the reactor helps to smooth out the wave forms that create reflected waves by absorbing the spikes that start it and burning them off as heat in the resistor. Reactors alone do very little toward that, despite commonly held beliefs. A DV/DT (technically, dV/dt for delta Volts over delta time) filter is good for distance of up to about 1200ft (YMMV), after which you should go to a Sine Wave filter, which is another step up in design. Sin Wave filters can take you to around 3,000 ft from drive to motor, so think along the lines of deep well ESPs.
I tend to use TCI rather than MTE, but that's just because TCI have invested a lot more time in helping me make sure my projects are successful, the local MTE reps just sell on price.
I tend to use TCI rather than MTE, but that's just because TCI have invested a lot more time in helping me make sure my projects are successful, the local MTE reps just sell on price.
Then just passive components.......
So what makes it a better type of sliced bread?
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Bread slices make for a lousy LRC low pass filter.
Dzboyce
Senior Member
- Location
- Royal City, WA
- Occupation
- Washington 03 Electrician & plumber
Yes I use the MTE DV/DT filter. I also use the TCI V1K. I mainly use them on submersible motors for pumps in wells. They are required for warranty purposes on any 460v 3 phase sub motor. They are recommended on 230v 3 phase motors but not required for the motor warranty.
most motors need a filter if they are more than 50 feet from the VFD. A simple line filter is usually acceptable up to about 300 feet. From 300 ft to 1200 feet you need a DV/DT filter, though for the small additional cost I use them for the under 300 ft application also. As Jraef mentioned, over 1200 ft distance you should be using a sine wave filter.
in 10 hp and under applications, I tend to use the TCI V1K. It's a little more expensive, but much more compact and quicker to install. I have discussed this with the MTE rep, and he's asked me to send a letter so that they can see what they can do about packaging the small filters in a more compact enclosure.
most motors need a filter if they are more than 50 feet from the VFD. A simple line filter is usually acceptable up to about 300 feet. From 300 ft to 1200 feet you need a DV/DT filter, though for the small additional cost I use them for the under 300 ft application also. As Jraef mentioned, over 1200 ft distance you should be using a sine wave filter.
in 10 hp and under applications, I tend to use the TCI V1K. It's a little more expensive, but much more compact and quicker to install. I have discussed this with the MTE rep, and he's asked me to send a letter so that they can see what they can do about packaging the small filters in a more compact enclosure.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Pretty much what he said, although I don't have a hard rule about 50' and over (unless, as he said, it's a warranty requirement). Some drive mfrs have tested distances from drive to motor and I have found those to be reliable, so if the VFD mfr says you can go 400' from drive to motor, I don't add a filter to that one. But not all drive mfrs do that, so the 50' rule is a good plan if you don't know. On the other hand if someone has a 460V motor that was not built as "inverter duty" and is so special that it cannot be exchanged with a newer version (which is the case on some machine tools), I do it regardless of length.
And I too prefer the TCI versions as well across the board.
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