Phares PE3 Industrial Tachometer
The Phares PE3 Industrial Tachometer is a microprocessor based, field mount device which detects pulses (12 VDC sinking), performs calculations based on the pulses and provides an LED readout in Revolutions Per Minute (RPM), Feet Per Hour (FPH), etc. The alarm relay setpoint and 4-20mA scaled output are factory programmed to customer specifications.
Normal configuration is a complete unit mounted in a NEMA 4 enclosure, with a viewing window to monitor the display. The enclosure includes: the tachometer circuit board, a relay, a step-down transformer, a 1A circuit breaker and a terminal strip for wiring input power, the sensor, 4-20mA signal, and the relay output.
Pulses can be provided by any sensor or encoder which meets the input specifications.
The circuit board is the heart of the Phares PE3 Industrial Tachometer. It contains the voltage regulators, signal filtering, microprocessor, digital to analog converter, seven-segment LED displays and their drivers. LED indicators are included to assist in troubleshooting. The microprocessor senses the incoming pulses, converts the period of the pulses to a rotational speed, and sets the drivers to the seven-segment LED display. Each microprocessor is programmed based on the speed range and pulse configuration of the application. The digital to analog converter drives the 4-20mA scaled output proportional to speed. The sensor wiring is protected internally to prevent the effects of short-circuiting of the sensor leads. The input voltage is clamped to prevent spikes from damaging the unit.
The relay indicates the speed condition. When speed is greater than the programmed minimum setpoint, the relay energizes and remains energized as long as the speed is greater than the minimum speed. The relay contacts are of the ‘Form C’ type, providing either normally open or normally closed contacts. There are three sets of contacts available on the relay.
The transformer converts the line voltage to a lower AC voltage. The circuit board and sensor operate on 12 Volts DC. The transformer steps the voltage down to levels suitable for rectification to DC. The transformer input can be either 120VAC or 240VAC, and is assembled at the factory for whichever voltage input is specified.
Enclosure and Wiring
The above components are assembled into a NEMA 4 rated enclosure. A window in the enclosure allows the tachometer speed to be read while operating. All wiring is complete. A terminal strip is provided for connecting field wiring. See the Enclosure specifications for sizes and mounting dimensions.
Figure 1. Phares PE3 Industrial Tachometer back panel and terminal strip.
Seven Segment LED,
4 or 5 Digit, with decimal point.
LED Height: 0.75″ (19mm)
0-10V and 4-20mA, proportional to speed
Quantity of 3 – NO, NC (Form C) Available
Contact Rating: 3A @125 VAC
Input Power: 100 to 240 VAC, 60 Hz, or 9-36 VDC
Current:Current: <1.0 A
Size: 10in. x 8in. x 6in.
Rating: NEMA 4
Weight: 15 lb.
Figure 2. Enclosure Dimensions