VFD reactors

[dinkelja]

Is it appropriate to install both a line ractor and load reactor (dV/dt filter) to combat: harmonics on the source feeders, and IGBT effects on long motor leads, respectively. I am assuming our motors were not spec'd as inverter duty rated. The various drives range from 30, 45, 75, and 100 hp @ 460V. Motors (pumps) are in washdown and GMP areas, so the MCC's are pretty far away, about 200 feet. (NEMA 4x drives are out of the question.) Also, is anyone really familiar with Allen Bradley VFD's. I cannot determine wether or not the line / load reactors are internal to the VFD buckets or are seperate and would be mounted on top of the MCC's for example.

 

[Skogsgurra]

Mains reactors and motor reactors (du/dt filter) has very different things to do. They are not mutually exclusive and can be installed in the same system.

Watch out for ringing across the motor reactors if the cables are long. You may need some damping there. Better talk to the VFD supplier.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[jraef]

Load reactors are the minimum you should employ if your motors are not inverter rated, maybe even if they are. In addition to the issue of long motor lead lengths, they also aid in allowing the VFDs circuit protection systems in preventing component damage under short circuit conditions on the load side by slowing down the rise time of the fault current.

Better that just a load reactor though is an LC filter system, sold by many of the same people as the simple reactors.

Line reactors are a minimal approach to harmonics on the line side. Better than nothing, but there are many better ways to approach it if you can afford it.

JRaef.com
"Engineers like to solve problems. If there are no problems handily available, they will create their own problems." Scott Adams
For the best use of Eng-Tips, please click here -> faq731-376

 

[VxA]

You can order AB MCCs with line & load reactors right in the MCC bucket from the factory (for less motors 75hp and less). For larger VFDs you will need an additional vertical section or enclosure.

http://www.ab.com/mcc/2_CENTERLINE_...s/2_Options/02_02_02_01.html#lineloadreactors

 

[Marke]

dv/dt filters on the output of the drive reduce the rate of rise of voltage on the output switching waveforms. This will reduce the charging currents into the cable capacitance as well as reducing the EDM effects on the motor bearings.
The reduced charging currents into the cable and motor capacitance will enable you to increase the potential length of the cable.
The Line reactors have two effects, they help to reduce the harmonics in the incoming line current and they build out the supply impedance so that the effects of the capacitive circuit to ground is reduced. The effects of the line reactors on reducing the output charging currents is often limited by capacitance added to the DC bus to ground to reduce the EMC radiation from the supply cables.
The best answer is to talk to the suppliers and find the best solution for your equipment and installation.

Best regards,

Mark Empson

http://www.lmphotonics.com