Operating Instructions

SED2 VFD NEMA Type 3R/3RHE Bypass Operating Instructions
4 Siemens Building Technologies, Inc.
SED2 VFD NEMA Type 3R/3RHE Bypass
Overview
During normal operation of a NEMA Type 3R/3RHE Bypass in a typical application, the input
and output contactors close and the SED2 operates the motor (Figure 1). The bypass
contactor provides the ability to operate the motor on utility power and eliminate the SED2
from the motor control circuit.
Drive
Motor
2 Contactor Bypass
Input
Device
Drive
Motor
3 Contactor Bypass
Input
Device
VFD0008R1
Figure 1. Functional Diagram of Typical NEMA Type 3R/3RHE Bypass.
The NEMA Type 3R/3RHE bypass consists of a SED2, NEMA Type 3R/3RHE bypass
enclosure, and controls. NEMA Type 3R/3RHE bypass components (Figure 2 and 4) include:
• Control terminal block
• "Drive-Off-Bypass" switch
• "Bypass On" light
• "Drive Test On-Off" switch (optional)
• Control Transformer
• Power fuses
• Relays
• Overload (current) relay
• Bypass Contactor
• Output Contactor
• Input Contactor (optional on the Type
NEMA 3R, standard on Type 3RHE)
• Motor Contactor
• Disconnect switch
• Heater