ELIS PLZEŇ a. s.
Design, Assembly and Service Manual
Page 4 of 32
Electromagnetic flowmeter FLONET FN50xx.1
ELIS PLZEN a. s., Lucni 425/15, 301 00 Plzen, Czech Republic, Phone: +420/377 517 711, fax: +420/377 517 722
Es90716K
1. APPLICATION
The FLONET FN50xx.1 electromagnetic flowmeter has been designed to measure volume flow rates of
electrically conductive liquids in closed piping systems. It enables flow measurement with high accuracy in a
wide range of flow rates (0.05 to 10 m/s) unlike the previous type FLONET FN20xx.1 (range 1:100) in
extended range 1:200.
It is supplied in a compact design (dismountable piece of flow sensor and
electronic unit) as a “blind”
(without a display) low-cost flowmeter for heat and cold measurement systems.
There is also a remote design of this flowmeter with a junction box on the top of chimney connected
to a cable with an electronic unit fitted with L-shaped steel angle bracket at the other end of the cable.
Power supply range is 230 VAC (or110 VAC). The flowmeter has only one galvanic isolated passive pulse
output OUT1.
The basic parameters can be set during activation process using special USB channel and sw FLOSET (it
isn’t standard in a delivery) .
2. MEASUREMENT PRINCIPLE
The function of an electromagnetic
flowmeter is based on Faraday’s induction law. The meter sensor
consists of a non-magnetic and non-conductive tube with two embedded measuring electrodes to pick up the
induced voltage. To create an alternating magnetic field, two coils are fitted onto the tube in parallel with the
plane defined by the active parts of the measuring electrodes. Now if a conductive liquid flows across
magnetic field
B
, voltage
U
will appear on the measuring electrodes proportional to the flow velocity v and
the conductor length
l
.
U = B x l x v
U
induced voltage
B
magnetic flux density
l
distance between the measuring electrodes
v
liquid flow velocity
As the magnetic flux density and distance between the electrodes are constant, the induced voltage is
proportional to the liquid flow velocity in the tube. The value of the volume flow rate can then be readily
determined as a product of the flow velocity and square section of the tube,
Q = v x S.
