962-5DA0-032 datasheet(2/12 Pages) MAGNETROL

2 / 12 page

P U L S E D

S I G N A L

T E C H N O L O G Y

Challenging process conditions such as

aeration,

suspended

solids,

and

high

viscosities are easily handled with the

pulsed signal technology utilized in the

961/962 switches. Pulsed signal circuitry

drives the transmit piezoelectric crystal

to produce powerful pulses of high-frequency ultrasonic

energy. These ultrasonic pulses are readily transmitted

through liquids, but are attenuated when the transducer

gap is dry. This technology also provides excellent immu-

nity from electromagnetic noise interference.

Pulsed signal technology makes the 961/962 units more

reliable than older continuous wave ultrasonic switches.

Unlike

many

tuning

forks,

pulsed

signal

ultrasonic

switches do not need to be configured for different media

densities, making these units the most universally applied

level switches on the market today.

Model 961/962 switches utilize ultrasonic energy to detect

the presence or absence of liquid in a single or dual point

transducer. Ultrasonic contact level technology uses high-

frequency sound waves that are easily transmitted across

a transducer gap in the presence of a liquid media, but

are attenuated when the gap is dry. Model 961/962

switches use an ultrasonic frequency of 2 MHz to perform

this liquid level measurement in a wide variety of process

media and application conditions.

The transducer uses a pair of piezoelectric crystals that are

encapsulated in epoxy at the tip of the transducer. The

crystals are made of a ceramic material that vibrates at a

given frequency when subjected to an applied voltage.

The transmit crystal converts the applied voltage from the

electronics into an ultrasonic signal. When liquid is present

in the gap, the receive crystal senses the ultrasonic signal

from the transmit crystal and converts it back to an elec-

trical signal. This signal is sent to the electronics to indi-

cate the presence of liquid in the transducer gap. When

there is no liquid present, the ultrasonic signal is attenu-

ated and is not detected by the receive crystal.

Ultrasonic

transducer

Transmit

crystal

Receive

crystal

Ultrasonic signal transmission

across transducer gap

T E C H N O L O G Y

B A S I C

O P E R A T I O N

S A F E T Y

I N T E G R I T Y

L E V E L

( S I L )

Critical process control applications demand reliable instru-

ments that provide high levels of safety. The introduction of

standards such as IEC 61508, IEC 61511 and ISA 84, have

generated interest in using Safety Instrumented Systems

(SIS) as a means to define the reliability

instruments

control

loop.

All

versions of the Model 961/962 switches undergo a detailed

performance evaluation called a Failure Modes, Effects and

Diagnostics Analysis (FMEDA). Three key components of

the FMEDA are the Safety Integrity Level (SIL), Safe Failure

Fraction (SFF) and the average Probability of Failure on

Demand (PFDavg).

961 Relay

961 Current Shift

962 Relay

962 Current Shift

SIL

2 as 1oo1

SFF

92.0%

91.4%

91.5%

91.8%

PFDavg

1.77E-04

1.61E-04

2.31E-04

1.87E-04

962-5DA0-032 Datasheet(PDF) 2 Page - Magnetrol International, Inc.

962-5DA0-032 Datasheet(HTML) 2 Page - Magnetrol International, Inc.

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12

Datasheet Download

Link URL