Honeywell FS-BKM-0001 Battery and Key Switch Module

The Honeywell FS-BKM-0001, also cataloged as the FS-BKM-0001 Battery and Key Switch Module, operates as a dedicated hardware component for system mode override, key-locked security execution, and backup battery power routing within Honeywell Safety Manager platforms.

Hardware Specifications

4-20 mA HART Loop Protocol and Channel-to-Channel Isolation

The module incorporates galvanically decoupled key switch contacts and isolated battery backup lines to maintain strict channel-to-channel isolation across internal system buses. High-impedance switching circuits (approx. 2 x 1.1 kohm output resistance in parallel) prevent high-voltage noise coupling into adjacent logic solver backplane lines. This isolation architecture prevents transient voltage surges on the 24 VDC auxiliary power rail from interfering with process control signals or 4-20 mA HART loop protocol instruments connected to adjacent safety I/O modules.

Frequently Asked Questions

Q: What key switch mechanism and electrical contact configuration are integrated into the FS-BKM-0001?

A: The module uses an SPST (Single Pole Single Throw) mechanical key switch rated for low-current control signal switching and hardware access control.

Q: What are the primary DC input power requirements for module operation?

A: The module requires dual supply inputs consisting of a 24 VDC line (18.4 VDC to 31.2 VDC range, 20 mA maximum current draw) and a 5 VDC bus line (+/-10%, 10 mA maximum current draw).

Q: Can the backup battery circuit be serviced while the primary 24 VDC power supply remains energized?

A: Yes, battery removal can be executed without disrupting 5 VDC logic backplane power, provided proper grounding and anti-static ESD procedures are observed during handling.

Field Installation Guidelines

• Isolate auxiliary power lines connected to the module rack location prior to inserting or removing the unit.
• Align the module card-edge connectors with the designated chassis rails and slide in smoothly until backplane headers seat completely.
• Tighten front panel retaining screws to secure mechanical grounding against the rack frame and ensure IP67 front face sealing.
• Connect backup battery wiring directly to designated isolated terminals, ensuring correct polarity alignment before restoring primary 24 VDC system power.