Specifications

G21
GE Limitamp
®
Medium Voltage Motor Control
Components
G
Description
The power-dip ride-through feature is available for critical
process applications where forced motor shutdowns are
very disruptive and where power system outages are
expected to last less than 20 cycles (333 milliseconds).
If a loss of power occurs while the main contactor M is
closed (see diagram) relays UV and MX transition to the de-
energized state. The normally-closed contact of UV and the
normally-open contact of MX in the coil circuit overlap as
they change state, thus avoiding an interruption of the
decaying coil current. The power to the main contactor coil
is removed but stored energy in the magnetic armature
keeps the contactor closed. After 20 cycles of outage (or less,
depending on MX relay time setting), MX (T.O.) contacts time
open and interrupt the decaying DC coil circuit, causing the
contactor to immediately open. The contactor will now remain
open until manually restarted by the START pushbutton.
If power is restored before the MX (T.O.) contacts time open,
the MX relay recloses to re-energize the main contactor coil,
maintaining the contactor tips closed throughout the outage
interval. Use 125VDC MX coil for 115-120 VAC control power
(60hz); or 110 VDC MX coil for 105-110 VAC control power
(50hz).
For a normal STOP operation (using the STOP pushbutton), it
is desired to bypass delayed contactor drop out. When the
stop pushbutton is pressed, relay MX normally-open contacts
open to remove power to both the AC and DC sides of the
Contactor Economizing Module (CEM). (The CEM provides,
among other things, the rectification of AC voltage to DC for
powering the main contactor coil).
CAUTION: Overload and other permissive interlocks such as
Multilin trip contacts must be non-failsafe. That is, they must
not open on loss of control voltage.
NOMENCLATURE
C – 10 MFD CAPACITOR (Cat
. NKE#18F232)
CEM - CONTACTOR ECONOMIZING MODULE
FILTER - R-C FILTER (Cat. 302A3847P1).
M - MAIN CONTACTOR (Types CR193 B, C, D&E)
MX – CONTROL RELAY W/TIMING HEAD
OL’S - PROTECTIVE RELAY CONTACTS
PB - PUSHBUTTON
RECT - RECTIFIER (Cat. 169B7656G2)
TDAD - TIME DELAY DE-ENERGIZATION
T.O. - TIME OPENING
UV – UNDERVOLTAGE RELAY (Cat. RL4RA22TJ)
Mounting means for 10 MFD capacitor – 129B8150G1
M
X
MX
T.O.
MX
MX
MX
UV
UV
1
15VAC
Control Power
1
15VAC
Control Power
*OL, etc. Stop PB
Start PB
MX
C
M
2
4
(+)
3
1
CEM
UV
M
F
ilter
TDAD
0.3 Sec
Rect
+
-
Adjustable Power-Dip Ride-Through