FW Murphy, 20700170, SS300 Series Electronic Speed Switch with SPDT Relay Dry Contact Output, Adjustable Differential, 12V, 625-9000 Hz
This is single set point speed switches with SPDT relay dry contact output. The trip point is set by a potentiometer. An LED indicates when the signal source is present. A second LED turns on when the trip point is reached. An optional time delay is on board to delay operation of the relay for 2-6 seconds after the set point has been reached.
Speed switch is intended for installation within a weatherproof enclosure to protect it from rain, dust, etc.
Overspeed shutdown. Shuts down the engine if RPM exceeds the preset limit.
Speed sensitive pull-in/drop-out. Engage or disengage PTOs, four-wheel drives, other switch points, etc. according to the engine speed being monitored.
Engine and transmission alarms/shutdowns. Oil pressure in some engines and transmissions varies widely between running and idle speeds. It can select between two pressure switch set points according to speed of the engine or transmission and thus give maximum protection to the equipment while at operating RPM and eliminate nuisance alarms when at idle.
Adjustable differential model. The AD can be adjusted to change the speed range over which the pull-in and drop-out differential of the relay will operate. A typical application is to ensure that engine speed is above a minimum RPM before applying a load but allows a drop in speed of several hundred RPM without disconnecting the load.
Applications:
- Generators
- Compressors
- Industrial Engines
- Pumps
- Vehicles
- Farm Equipment
For more information, please see 
Data Sheet
