Download Ground fault circuit interrupters (GFI) are circuits

LEAKAGE CURRENT SUPPRESSOR (LCS)
The objective to reach is significant reduction of leakage current
when an electric motor is used with an adjustable frequency
drive.
Ground fault circuit interrupters (GFCI) are circuits that measure the differential
current between active wires and therefore detect the amount of current returning
to ground. The trip limit for US GFCIs is 5mA @ 60Hz. The switching of the
motor parasitic capacitance creating MHz current spikes may induce a trip of the
breakers when no ground fault occurred. Reduction of these high frequency
leakage currents is mandatory to avoid nuisance tripping of GFCIs during normal
operation.
When a motor is connected to an AFD, the parasitic capacitor within the drive
itself withstands voltage swings proportional to the switching speed of the power
electronic switches, hence up to 5000V/μs. These high frequency high amplitude
voltage spikes create very high frequency currents (up to MHz range) across the
capacitor. The motor isolation (flex circuit) is connected to the electronic drive
ground where the leakage current is isolated from the GFCI, thereby eliminating
nuisance tripping.
The innovative technology developed by RBEM (patent in process) allows
significant reduction of leakage current while keeping the motor specifications
identical. The only identifiable external change is an additional lead wire exiting
the motor with the normal connections (black wire).
In order to reduce these leakage currents to an acceptable level an insulator
comprising of metallic layers sandwiched between two insulative layers were
added to each stator. See the below picture of this added insulator prior to it
being folded up and laced to the end turns.
LCS MOTOR PLATFORM
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Platform: CASA 40fr, 3PH product line, 6.4” diameter stators
Voltages: 230V, 460V
Construction: TEFC, Open, DP, TEAO
Speeds: 4P, 6P
Mountings: Welded base, Resilient base, 56fr C-face, Extended Clamp
Bolts
Current Applications
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Industrial Mixers
Swim spa (continuous Wave Pools)
Potential Opportunities
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Bearing current suppression