OS77 Series Single Set Point Switch
Installation and Operation Instructions
OS-98001N
Effective 04-98
Section 20
00-02-0303
Description
The OS77 Series single set point speed switch is a compact, all-electronic,
speed sensing module. It is field adjustable and can be panel mounted via its
trip set point potentiometer.
Standard OS77 models provide a transistor output when tripped. Models with a
relay output are available.
The OS77 is used for protecting the engine from excessive or insufficient oper-
ating speeds. As the engine speed reaches the adjustable set point setting, the
OS77 will cause the engine to shutdown.
Models are available with Normally Open or Normally Closed circuit and
available recrank feature which inhibits starter re-engagement until the engine
speed is near zero RPM.
Specifications
Power Supply: Voltage: 7-28 VDC.
Maximum Current: 100 mA.
Frequency Signal:
Voltage, Magnetic Pickup Signal Models
•
Minimum: 1.2 Vrms
•
Maximum: 30 Vrms
Voltage, Distributor Ignition Models
•
Minimum: 6 Vrms
•
Maximum: 30 Vrms
Maximum Current, Magnetic Pickup Signal Models: 0.12 mA
Maximum Current, Distributor Ignition Models: 0.12 mA
Adjustment Range, Magnetic Pickup Signal Models: 1000-10,000 Hz
Adjustment Range, Distributor Ignition Models: 40-400 Hz
Reset Differential, Magnetic Pickup Signal Models
•
Non-recrank model: 10 Hz Differential
•
Recrank model: dropout 54 Hz
Reset Differential, Distributor Ignition Models
•
Non-recrank model: 10 Hz Differential
•
Recrank model: dropout 2.4 Hz
Output:
•
Transistor Sink to Ground Resistive Load: 2 A, 28 VDC
•
Relay Output Models: 5 A, 250 VAC
Adjustment: 270°–turn potentiometer
Temperature Range: -13° to 185°F (-25° to 85°C)
OS77 Module Dimensions
Please read the following information before installing
.
A visual inspection of this product for damage during shipping is recommended
before mounting. It is your responsibility to have a qualified person install this unit and make sure it conforms to NEC and local codes.
GENERAL INFORMATION
Installation Accessories
Hardware tools and optional equipment needed to install the OS77:
●
Tools as needed for system mounting such as drill and screw driver
●
18 AWG wire for extension and hook up
●
Wire termination tools and ring or spade wire termination.
●
Voltmeter or test lamp for set up and adjustments.
®
FRANK W.
MFR.
WARNING
BEFORE BEGINNING INSTALLATION OF THIS MURPHY PRODUCT
✔
Disconnect all electrical power to the machine.
✔
Make sure the machine cannot operate during installation.
✔
Follow all safety warnings of the machine manufacturer.
✔
Read and follow all installation instructions.
OS77 Series
1
5
2
3
4
2-1/2 in.
(64 mm)
2-3/8 in.
(60 mm)
2-1/8 in.
(54 mm)
Panel
Mounting
Hardware
Potentiometer
Locknut
Speed Adj.
Potentiometer
Speed Adj.
Potentiometer
Polycarbonate
enclosure
Terminal #5 used for
Relay output models
Positioning
post
Mounting Instructions
The OS77 module is designed to be mounted in a flat panel.
1.
Drill the mounting holes as shown on the template included with the packing.
2.
Insert the module from the back side of the panel (refer to schematic above).
3.
Secure the OS77 module using the mounting hardware included.
Mounting Schematic
