User Guide

2-10 Installation MN850
NEMA 12/4 Installation When a NEMA12, NEMA4, NEMA4x OR IP65 enclosure is used, a separate Top of Ramp
Bypass (or shunt) contactor must be connected in parallel with the soft–start control. This
will allow a solid connection of the motor to the AC power lines and eliminate the heating
effect caused by the SCR’s. At the completion of the start ramp (when full start voltage is
obtained) a Bypass contactor is closed. This contactor is controlled by the “Top of Ramp”
relay K2. This ensures that bypass will only occur when motor voltage equals the AC line
voltage.
Figure 2-6 Top of Ramp (Bypass) Connection
L1 L2 L3
Baldor
Digital
Soft–Start
See Recommended Tightening Torques in Table 2-4.
T1 T2 T3
K1
K2
S1
S0
X1
X2
* BC Bypass
Contactor
115/230VAC
BC
Fuse
Neutral
* External hardware not provided with control.
K2 is factory preset
as the Top of Ramp" function.
Note:
Add appropriately rated
protective device for AC
relay (snubber) or DC
relay (diode).
To AC Input
To Motor
14
11
24
21
22
12
To protect the control, be sure to add MOV protection.
Refer to Appendix D for additional information.