Five Reasons You Should Buy Motors with AEGIS Shaft Grounding Rings Factory-Installed Inside
1. Motors run on variable frequency drives (VFDs) need protection against bearing currents
VFDs are widely used for the energy savings they can provide. But without bearing protection, these savings can be lost. Because VFD output power is not balanced (i.e., the voltage of the three phases does not sum to zero), VFDs create a capacitive voltage on the shafts of the motors they control. These shaft voltages will try to discharge to ground by the lowest-resistance path available to them. Usually, the path of least resistance lies through the bearings, so that's where discharge will occur, in the form of an electrical arc. These arcs create pits in the bearing surface. Although these pits are individually tiny, arcing can occur thousands of times per second, and each arc creates a new pit. The damage due to pitting is cumulative and can cause bearing failure in as little as a few months.
AEGIS® Shaft Grounding Rings offer a lower-resistance path for these discharge currents. Because the bearings have higher resistance than an AEGIS ring, these currents preferentially flow through the ring, not the bearing. Without discharge currents constantly flowing through the bearing, the bearing will last as long as it was designed to, and users will be spared the costs of frequent motor repair and the downtime it entails. For an ROI analysis of AEGIS shaft grounding, see this post.
2. Internal installation protects the AEGIS Ring
Compared to other methods of shaft grounding, AEGIS rings are highly resistant to contamination and other environmental factors. Nevertheless, excessive amounts of dust, debris, and grease can interfere with the ring's function, and mounting the ring inside the motor frame protects it from these detrimental influences.
3. Factory installation saves you time
While AEGIS rings are not difficult to install, it's even easier, and quicker, to buy a motor with a ring already installed.
4. Factory installation saves you money
A motor with AEGIS factory installed will cost less than a similar motor without AEGIS plus the cost of the ring, plus the value of the time it takes to install the ring.
5. You've got options
Many of the best-known motor manufacturers offer motor lines with AEGIS factory-installed inside. ABB Motors and Mechanical (formerly Baldor), GE, LEESON, Marathon, and WEG all offer AEGIS inside their inverter duty motors. For the list of all motor manufacturers who offer AEGIS shaft grounding rings factory installed (inside or outside the motor), see this page.