Toshiba lf516 Manual De Usuario

 
 

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The operating principle of the electromagnetic flowmeter is based on Faraday's Law of electromagnetic 
induction and it is designed to measure the volumetric flow rate of fluid. An insulated pipe of diameter D is 
placed vertically to the direction of a magnetic field with flux density B (see Figure 14.1). When an 
electrically conductive fluid flows in the pipe, an electrode voltage E is induced between a pair of 
electrodes placed at right angles to the direction of magnetic field. The electrode voltage E is directly 
proportional to the average fluid velocity V. 

The following expression is applicable to the voltage. 

 

E = K × B × D × V [V] ........ (Eq. 14.1) 
 
 
Volumetric flow rate Q [m

3

/s] is: 

 
Q =         × V ................(Eq. 14.2) 
 
Using the Equation 14.1 and 14.2 

 

E = K × B × D ×         × Q 
 
E =           × Q ............(Eq. 14.3) 
 

Therefore, volumetric flow rate is directly proportional to the induced voltage. 

 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

LF516/LF546 lectromagnetic flowmeter uses the square-wave excitation method, which provides 
long-term stable operation. With square-wave excitation, LF516/LF546 offers reliable measurement 
without being affected by electrostatic or electromagnetic interference, or electrochemical polarization 
between the electrodes and the fluid to be measured. 

  E = induced electrode voltage [V] 
  K = constant 
  B = magnetic flux density [T] 
  D = meter pipe diameter [m] 
  V = fluid velocity [m/s] 

π

 × D² 

4

      4 
π

 × D²

4 × K × B 
  π × D 

Square-Wave Excitation 

B 

V 

E 

D