Bypass Control - Toshiba G3 Workbook

Introduction
Among the many special functions the G3 can realize is a inverter/bypass control. Bypasses are utilized to
provide operation of the motor across-the-line (ATL) in the event of a drive fault or during inspection of
the drive. All devices shown external to the drive will have to be provided. The bypass scenario can also
make use of the drive's ability to "catch" a spinning motor, which is useful when transferring an ATL
motor to the drive.
Connections
MCCB
3
Enable
Inverter
Bypass
Notes
The contacts are shown in an unenergized coil state.
An additional contactor may be included to isolate the drive, thereby allowing the cycling of drive
power while in bypass.
An overload relay (OLR) is necessary in a bypass scenario because the drive's built-in motor thermal
protection is not in the circuit in the bypass mode.
A normally open (NO) contact from the OLR should be put across the S1 and CC terminals of the
drive.
The interposing relays (R3 and R4) shown above may not be necessary; the RCH and LOW output
contacts of the G3 are rated for 250 VAC, 1 A for inductive loads; compare with the burden of your
bypass and output contactors' coils.
For additional assistance, please contact Toshiba Adjustable Speed Drive Marketing Dept. at (800) 872-

Bypass Control

C4
G3
ST
S2
F
CC
2192
C3
V(+)
RCH A R1
LOW A R2
LOW C
RCH C
Overload
Relay
CONTROL
C1
C2
R4
R3
V(-
14
M
29