
INTRODUCTION
The K-Factor scaler is a field adjustable frequency divider, which interfaces the output signal from a turbine meter with a
magnetic pickup to the input of a PLC, RTU, CPU data acquisition card or similar totalizer device. The adjustable frequency
divisor, referred to as the K-factor, allows the pulses being sent from a turbine meter to be divided into a recognizable unit
that an end device, such as a PLC, can count and display.
Different K-factors allow the device to display in any number of volume measurements such as gallons, cubic meters,
liters, barrels and like units. A calibration sheet provided with a turbine meter lists a nominal K-factor or other frequency
information specific to that particular flow meter, tested to a specific volumetric flow rate. This K-factor can be placed directly
into the K-factor scaler to provide an output with the same volumetric flow rate or modified to a different volumetric flow rate
by recalculating the K-factor with the appropriate conversion factor.
In addition, if the K-factor is set to one, the K-factor scaler can be used as a preamplifier where the frequency from a low level
turbine meter is proportional to the logic level frequency output needed by a PLC or CPU data acquisition card. This option
allows the end device to control the dividing process of the turbine meter output to a recognizable flow rate.
OPERATING PRINCIPLE
Fluid moving though a turbine flow meter causes the rotor to rotate in relation to the flow rate. The rotation of the rotor
blades cuts through the magnetic field generated by the magnetic pickup, which generates a frequency output signal that is
directly proportional to the speed of the rotor.
Turbine Rotor
Magnetic Pickup
or
Other Frequency
Output Device
Output
Figure 1: Schematic illustration of electric signal generated by rotor movement
The signal produced is received by the K-factor scaler input amplifier, which has an input sensitivity of 30 mVp-p…30Vp-p. The
signal is then sent to an onboard microcontroller, which acts as a divisor with a range of 1…999,999,999. The divisor (K-factor)
is user adjustable and set by programming it into the board. The microcontroller handles the dividing process by counting the
input pulses and comparing it to the programmed K-factors. Once the count equals this value, an output pulse occurs for a
selectable time period and the counting process starts over.
Introduction
Page 6 June 2021SGN-UM-00281-EN-06