OS-98001N
Effective 04-98
Section 20
OS77 Series Single Set Point Switch
Installation and Operation Instructions
00-02-0303
®
FRANK W.
MFR.
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
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
Description
OS77 Module Dimensions
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.
Speed Adj.
Potentiometer
2-1/2 in.
(64 mm)
2-3/8 in.
(60 mm)
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.
2-1/8 in.
(54 mm)
1
2
3
4
5
Mounting Schematic
Specifications
Polycarbonate
enclosure
Positioning
post
Power Supply: Voltage: 7-28 VDC.
Maximum Current: 100 mA.
Frequency Signal:
Mounting
Hardware
Voltage, Magnetic Pickup Signal Models
•
•
Minimum: 1.2 Vrms
Maximum: 30 Vrms
Potentiometer
Locknut
Panel
Voltage, Distributor Ignition Models
•
•
Minimum: 6 Vrms
Maximum: 30 Vrms
Speed Adj.
Potentiometer
Terminal #5 used for
Relay output models
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
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.
•
Non-recrank model: 10 Hz Differential
Recrank model: dropout 54 Hz
•
Reset Differential, Distributor Ignition Models
Installation Accessories
•
•
Non-recrank model: 10 Hz Differential
Recrank model: dropout 2.4 Hz
Hardware tools and optional equipment needed to install the OS77:
●
●
●
●
Tools as needed for system mounting such as drill and screw driver
Output:
18 AWG wire for extension and hook up
•
•
Transistor Sink to Ground Resistive Load: 2 A, 28 VDC
Relay Output Models: 5 A, 250 VAC
Wire termination tools and ring or spade wire termination.
Voltmeter or test lamp for set up and adjustments.
Adjustment: 270°–turn potentiometer
Temperature Range: -13° to 185°F (-25° to 85°C)
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