Operating Instructions

SED2 VFD NEMA Type 3R Bypass Operating Instructions
54 Siemens Building Technologies, Inc.
Troubleshooting
Description of Problem Possible Cause
• Commanding the SED2
to start closes the bypass
contactor.
SED2 required programming for bypass operation has not been
programmed in the VFD. Make appropriate VFD programming
changes. See Required SED2 Parameter Setting.
• Contactors do not close. • Main input short circuit protection has opened.
• Control power fuse has opened.
• Safety circuit is open.
• Motor overload needs to be reset.
• Loose control wire connection.
• Drive does not start on
closing of bypass control
terminals 1 and 2.
• Drive–Off–Bypass switch is not in the drive position.
• Drive output contactor is not closed.
• Remote contact is not really closing, replace with a wire jumper or
use drive parameters to verify this contact closure.
• Run relay has failed.
• Loose control wire connection.
• Drives digital input 1 is not programmed appropriately.
• Main input fuses clear
when motor is run in
bypass
• The short circuit protection supplied by the factory is
approximately 1.5 times NEC listed motor current rating.
• Some applications and motor characteristics may require up sizing
this protection. If this is required in the field, ensure that there is an
appropriate match between the fuse type and rating with fuse
holder. Also ensure appropriate UL guidelines are followed. If
unsure, contact field support.
• VFD tripping on over
temperature
• Ensure that NEMA Type 3R Bypass enclosure input air filter is
clean and free of obstruction.
• Ensure that NEMA Type 3R Bypass enclosure fan is operational
(The fan operates only when the drive is running.)
• Ensure that NEMA Type 3R Bypass is within its rated operating
environment of 14°F to 104°F (–10°C to 40°C) and 0 to 95% rh,
non-condensing. NOTE: HT1 units are rated to 122°F (50°C).
• Ensure that all SED2 cooling fans are operational.