The Cutler-Hammer FD120, part of Eaton's DIESEL Plus series, is a microprocessor-based fire pump controller engineered for 12 or 24 VDC diesel engine-driven fire pumps. Listed to UL 218 and approved to FM 1321/1323, it provides the automatic and manual control, alarm supervision, and battery management required by NFPA 20 for fire protection systems in commercial, industrial, and institutional facilities.

How does the FD120 interface with modern diesel engine ECUs?

The controller supports CANbus SAE J1939 communication with the engine's electronic control module (ECM), allowing it to read engine speed, oil pressure, coolant temperature, fuel consumption, and diagnostic trouble codes directly from the engine ECU — eliminating redundant discrete sensors and wiring. For mechanical engines without an ECM, the FD120 accepts conventional discrete inputs from oil pressure switches, temperature switches, and speed pickups. Up to 10 additional programmable inputs accommodate field-specific requirements such as low fuel, low suction, relief valve position, and reservoir level.

What battery and charging management does it provide?

Dual 10 A current-limiting solid-state switching chargers independently maintain both starting batteries, with automatic detection of 12 or 24 VDC nominal voltage and support for lead-acid or nickel-cadmium battery chemistries. Each charger provides three-step charging with reverse polarity protection, internal temperature monitoring, and diagnostic recording. The controller continuously monitors battery voltage and charger status, annunciating Battery #1/#2 Failure and Charger #1/#2 Failure alarms on the backlit 4-line × 40-character LCD display and via dedicated alarm relay contacts.

Can the FD120 be monitored remotely?

Standard USB connectivity enables on-site history download, statistics review, diagnostics, and firmware/language updates via a laptop. An optional Ethernet port provides an embedded web page displaying real-time controller status, setpoints, and diagnostics accessible from any browser on the facility network. Optional RS485 Modbus RTU/ASCII integration connects the FD120 to building management systems and SCADA hosts for centralized alarm monitoring. All alarm relays — including common alarm — are fail-safe, energizing under normal conditions and de-energizing on power loss or fault to guarantee alarm annunciation.