TEIP11, TEIP11-PS
| 42/18-46-EN Rev. L 7
3
Function and system design
The I/P signal converter converts standard electrical signals,
e.g. 4 … 20 mA to 0.2 … 1 bar (3 ... 15 psi). It therefore forms
a connecting link between electrical/electronic and pneumatic
systems. The signal conversion process is similar to the
patented force balance method.
Special features of the I/P signal converter are its relatively
small dimensions and outstanding operational stability when
subjected to shock and vibration. The I/P signal converter can
be subjected to loads up to 10 g with less than 1 % effect on
function.
The housings are available in a variety of designs to meet your
installation requirements. For potentially explosive conditions,
devices offering intrinsically safe operation or with a flameproof
housing enclosure are available with international approval
certificates for use worldwide.
Various ranges can be supplied on the input side and the
output side for signal conversion (see section "Additional
documents" on page 14).
The device requires only compressed air for the power supply.
3.1
Principle of operation
Fig. 1:
Schematic structure
1
Coil
2
Yoke
c
Air gap
d
Magnet
e
Flapper
f
Nozzle
g
Throttle
h
Power stage
i
Lever arm
j
Potentiometer
k
Resistor
l
Filter
m
Air supply
Force balancing takes place at the lever arm, which is
mounted with a tension band. The coil and yoke generate a
magnetic field in the air gap, which applies a force to the
magnet on the lever arm. The force changes in proportion to
the current (input signal) flowing through the coil.
A counterforce is applied on the other side of the lever arm,
through the dynamic air pressure present at the nozzle and
the flapper. The force is controlled in such a way that a
balance of the two torques is achieved. If a torque imbalance
occurs, the lever arm rotates. This rotation changes the air
gap between the nozzle and the flapper and, thus, the
dynamic air pressure. Air is permanently supplied to the nozzle
through the throttle. The power stage converts the dynamic air
pressure into a 0.2 ... 1 bar or 3 ... 15 psi output signal.
Supply air
During operation the pneumatic unit needs a steady supply of
air in accordance with the device specifications. The zero
point setting is adjusted by turning the tension band
suspension, and the range setting is adjusted via the
potentiometer.
Filter
The filter prevents malfunctions caused by polluted supply air.
Note that the filter capacity is only sufficient for collecting dirt
that occurs occasionally (e.g. residual dirt in the pipe during
initial commissioning). It is no substitute for proper air
conditioning.
3.1.1
Special features
Special features of the TEIP11, TEIP11-PS I/P signal converter
are its relatively small dimensions and outstanding operational
stability when subject to shock and vibration. The stability is
due to the light weight (only around 100 mg) of the moving
system, which consists of the lever arm with the magnet and
the flapper with balancing weight.
3.1.2
Deliverables
Details of the available I/P signal converter variants and
accessories can be found in the data sheets. The data sheets
also indicate each item’s order number.
M10918
1
2
3
7
6
8
9
0
k
l
5
4
m
0 … 20 / 4 … 20 mA
0,2 … 1 bar (3 … 15 psi)
1,4 bar (14.5 psi)
