PRAS1 Datasheet, PDF (5/52 Pages) ASM GmbH – Angle Sensors and Encoders Contents

POSIROT ^® / POSITILT ^®
Angle Sensors and Encoders 
The Functional Principle
PRAS/PRDS Series (POSIROT^®)
The angle sensors of the PRAS/PRDS series are
­based on a contact-free and absolute measure-
ment principle. The position sensing element is a
permanent magnet.
Depending on the permanent magnet type, a to-
lerance in the air gap and axial offset is ­allowable
within certain limits. The detected magnetic field
vectors are transformed by an internal circuit
board into standard 4-20 mA, 0.5-10 V and SSI
output signals.
PMIS Series (POSIROT^®)
The incremental encoder of the PMIS series con-
sists of an XMR sensor head and a magnet ring
as a ­ magnetic scale. The circumference of the
magnet ring contains a series of evenly spaced
magnetic north and south poles.
The angular position is determined contact-free
and wear-free by the sampling of the sinusoid
­magnetic field above the surface of the magnet
ring by the XMR-sensor head. The air gap ­between
the sensor head and the magnetic ring can be up
to 2 mm for a ring with a 5 mm period. The sensor
head generates 90° shifted sine/cosine signals,
through the integrated signal interpolation circuit,
these ­ signals are combined with the reference
mark signal and transformed without a time delay
into a square-wave output.
PTAS Series (POSITILT^®)
The PTAS series uses a pendulum with an inter-
nal position magnet to provide the inclination an-
gle. The cavity surrounding the pendulum is filled
with a specific fluid that can be varied depending
upon the amount of motion damping is required.
The established PRAS2 or PRDS2 angle sensor is
fitted into the PTAS2 housing. The stainless steel
housing is thoroughly sealed and is rated up to
IP69K, which makes it suitable for use in extreme
environments found on cranes, off-highway con-
struction equipment, ships and off-shore applica-
tions.
External magnetic fields due to power cables,
magnetized materials or the earth’s magnetic field
do not influence the accuracy of the inclinometer.
The PTAS series is completely encapsulated in
a magnetically shielded housing and is immune
against magnetic fields as far as possible.
ASM
www.asm-sensor.com
CAT-PR/PT-E-07