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Section 7: Bypass system
Purpose
Bypass control provides for those times when an SC9000 EP
AFD is taken offline and the connected motor must run.
This chapter addresses the Eaton SC9000 EP bypass control
products.
Types of SC9000 EP bypass
There are two types of bypass control generally applied with
SC9000 EP products:
Full voltage bypass
●
RVSS Bypass
●
Full voltage bypass
This system switches an induction motor's power source
between two sources: a utility source and an SC9000 EP
AFD. Use Full voltage bypass when the AFD requires
maintenance or troubleshooting. It allows the motor to
connect to the incoming line, bypassing the AFD and
performing a full-voltage start.
The motor and connected equipment must be able to
tolerate an across-the-line start without mechanical or
electrical damage. Fan or pump applications are examples
of systems where a full-voltage start can work without
connected equipment damage.
Representative panel layout diagram
Figure 85. Representative full voltage bypass
panel layout
Sequence of operation
Control Elements colors and symbols
Under normal conditions, the SC9000 EP powers the motor,
and the bypass contactor is open, isolating the motor from
the AC power feed bus.
Figure 86. Normal operation using SC9000 EP AFD
When the AFD is not available, the AFD input contactor
is open, the bypass contactor AC line feeder contactor
closes, the AFD output contactor opens, and the AC line
feeds the motor.
Figure 87. Full voltage bypass operation
SC9000 EP medium voltage drives IB020001EN—February 2016 www.eaton.com
Appendix D: Optional equipment
= de-energized
= contactor closed
= energized feeder bus
79
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