Operating Instructions

Migration Guide SED2 to BT300 Variable Frequency Drives
Document Number 125-1005
January 12, 2015
Page 8 Siemens Industry, Inc.
Interlock
Description
The Interlock feature (also called damper end switch logic) enables the BT300 to inhibit
motor start until a safety condition (proofing sequence) is confirmed. Any call to start
the motor from the BT300 or bypass does not directly start the motor, but instead
initiates the following Interlock procedure:
1. The Interlock Start Logic Enable indicator is ON. Proofing is required to start in
VFD or bypass mode.
2. The Interlock Start Logic Command indicator turns ON and the Proofing
indicator flashes.
3. In VFD mode, the BT300 Relay closes and the Controller Board
Programmable Output closes to initiate the proofing sequence. The
Programmable Output relay is used to supply power to an external device such
as a damper actuator.
4. When not in VFD mode, the Controller board ignores the BT300 Relay.
5. In bypass mode, any call to start the motor in bypass (in either hand-bypass or
auto-bypass) initiates the proofing sequence.
6. The Programmable Output closes and is used to supply power to an external
device such as a damper actuator.
7. When control of the external device (such as a damper actuator) is satisfied, it
must supply a contact closure to the Controller board Interlock Start.
8. The Interlock Start Logic Command indicator turns OFF and the Proofing
indicator turns ON.
9. The motor then starts in the selected mode.
10. Any call for the motor not to be running requires a new proofing sequence to
be initiated.
NOTE: This feature can only be used with a hardwired start/stop command.
Settings
DIP Switch
The Interlock feature requires that the SED2 Electronic Bypass Controller board DIP
Switch 3 is set ON.
NOTE: The Interlock Start Logic Enabled indicator is on steady.
Figure 5. DIP Switch Setting.