Murphy MTH6 - Manual

■ Tachometer and Hourmeter With
Overspeed Shutdown or Alarm Switch
■ 3-1/2 Inches (89 mm) Diameter Dial
■ Reads RPM Data from a Magnetic Pickup or
Battery Charging Alternator
■ Powered by 8 to 40 VDC
■ Large 5-Digit LCD Display
■ Maintains Hours Count When Power Is Lost
■ Front Panel Programming
■ Hours Can Be Reset to Zero
Model MTH6
Description
This microprocessor-based digital tachometer
and hourmeter with a built-in overspeed
switch is highly accurate and dependable. It
measures speed and running hours and can give
an alarm or shut down the engine on
overspeed.
The MTH6 case is polycarbonate, and its dial
measures 3-1/2 in. (89 mm) in diameter.
RPM data for the tachometer and overspeed
switch is supplied by a magnetic pickup or
battery charging alternator. The magnetic
pickup is installed into the flywheel housing
of an internal combustion engine. The starter
ring gear acts upon the magnetic pickup to
generate a voltage pulse each time a gear tooth
passes the end of the sensor.
Applications
Basic Operation
During normal operation, the MTH6 displays
RPM. Its five-digit, liquid crystal display is
updated every second. When the MTH6 is
displaying hours and a speed signal is present,
the far left digit and decimal point will flash
indicating the hourmeter is operating.
The overspeed set point and running hours
can be viewed by manipulating three mem-
brane switches located on the MTH6 front
panel.
When the overspeed set point is met an LED,
also located on the front panel, lights.
Easy-Calibration
The MTH6 calibration is simple. The operator
enters the number of pulses per engine revolution
and the overspeed set point value using the mem-
brane-switches located on the front of the
MTH6.
Specifications
Power Requirements:
8-40 VDC (12, 24 or 32 VDC systems).
Maximum Current:
12 VDC: 0.011 A, backlight Off;
0.025 A, backlight On.
24 VDC: 0.008 A, backlight Off;
0. 015 A, backlight On.
32 VDC: 0.007 A, backlight Off;
0. 010 A, backlight On.
Operating Temperature: -4° to 158°F
(-20° to 70°C).
Storage Temperature: -40° to 185°F
(-40° to 85°C).
Case: 1018 Polycarbonate/Polyester blend.
Mounting Hole Dim.: 3-3/8 in. (86 mm)
Dia.
Speed Input: 4.5 Vrms minimum.
Overspeed Switch Rating: 2 A, 50 VDC.
Overspeed Range: 0 to 9000 RPM.
Pulses per Revolution: 4 to 255.
Tachometer Range: 0 to 65,535 RPM.
Tachometer Accuracy: ±1% of the display
reading or -2 RPM whichever is greater.
Input Frequency Range: 25 Hz to 20 kHz.
Hourmeter Range: 0 to 99999 hrs.
Hourmeter Resolution: ±0.1 Hour up
to 9999.9; ±1 hour 10,000 and up.
Reset Hourmeter: Apply temporary ground to
terminal #5 to reset hours to zero.
Shipping Weight: 14 oz. (435 g).
Shipping Dimensions: 5-1/2 x 5-1/2 x
5-1/2 in. (140 x 140 x 140 mm).
• Industrial Engines
• Generators
• Compressors
• Oil Field
Equipment
• Marine Engines
• Vehicles
• Farm Equipment
• Construction
Equipment
MTH-96115B
Revised 02-04
Catalog Section 20
(00-02-0777)
Digital Tachometer and Hourmeter
With Adjustable Overspeed Set Point