MMF KSI84 Series User manual

Instruction Manual
Manfred Weber
Metra Mess- und Frequenztechnik in Radebeul e.K.
Meissner Str. 58 - D-01445 Radebeul
Tel. [phone] Fax [phone]
Email: [e-mail] Internet: www.MMF.de
4-20 mA
Vibration Sensor
Type
KSI84xx
v1.32.030

2
Published by:
Manfred Weber
Metra Mess- und Frequenztechnik in Radebeul e.K.
Meißner Str. 58
D-01445 Radebeul
Tel. [phone]
Fax [phone]
Email [email protected]
Internet www.MMF.de
Note: The latest version of this document can be found at:
https://www.mmf.de/product_literature.htm
All rights reserved, including those of translation.
Subject to modifications.
© 2021 Manfred Weber Metra Mess- und Frequenztechnik in Radebeul e.K.
Edition: 15.11.2021

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Contents
1Purpose.....................................................................................................4
2Function....................................................................................................4
3Type Selection..........................................................................................5
3.1 Frequency Range (HP, LP).................................................................5
3.2 Measuring Range................................................................................6
3.3 Type Code ..........................................................................................6
4Sensor Operation.....................................................................................7
4.1 Sensor Mounting.................................................................................7
4.2 Sensor Connection .............................................................................7
4.2.1 Connection to the Loop Supply..................................................7
4.2.2 Sensor Cable.............................................................................8
4.2.3 Grounding Concept....................................................................8
4.3 Connection of the Measuring Device..................................................9
4.3.1 Maximum Load Resistance RL...................................................9
4.4 Sensor Self-Test...............................................................................10
4.5 Measuring Mode...............................................................................10
4.5.1 Sensitivity Bi.............................................................................10
4.5.2 Calculation of Acceleration and Velocity..................................10
4.5.3 Offset Current and Noise .........................................................11
4.5.4 Linear Measuring Range xmin…xmax .........................................11
4.5.5 Maximum Dynamic Range.......................................................12
4.6 Overload Display...............................................................................12
4.7 Averaging Filter.................................................................................12
4.7.1 Number of Averages N.............................................................12
4.7.2 Settling Time T.........................................................................13
4.8 Total accuracy...................................................................................13
4.9 Error Messages.................................................................................14
4.9.1 Steps to Fix a LOOP Error.......................................................14
5Technical Data........................................................................................15
5.1 Technical Characteristics of the 4-20mA Signal Conditioning...........15
5.2 Electrical Characteristics...................................................................15
5.3Mechanical Characteristics...............................................................15
5.4 Environmental Characteristics ..........................................................15
5.5 Type Tables......................................................................................16
5.5.1 Acceleration, RMS ...................................................................16
5.5.2 Acceleration, PEAK..................................................................17
5.5.3 Velocity, RMS ..........................................................................18
5.5.4 Velocity, PEAK.........................................................................18
Limited Warranty........................................................................................19
Declaration of Conformity.........................................................................19

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1 Purpose
The vibration sensors of the KSI84xx family are used to measure vibration
acceleration or velocity on machines and objects.
The sensors measure the vibration amplitude within a specified frequency range in
axial sensor direction and outputs the measuring result as a 4-20 mA current loop
signal. The sensor is supplied with power via the same signal line.
The sensor parameters are adjustable. There are different types for different appli-
cations in several measuring ranges. The sensors comply with the specifications for
vibration measuring devices according to ISO 2954.
Possible applications are:
1. Measurement of the smooth running of rotating machines and
reciprocating machines according to ISO 10816 / ISO 20816.
2. Measurement of bearing vibrations according to VDI 3832.
3. Measurement of vibrations in defined frequency ranges.
The sensors are suitable for use in harsh environmental conditions. The housing is
double shielded, electrically isolated and complies with protection grade IP68.
2 Function
The sensors of the KSI84xx family are piezoelectric vibration sensors.
A piezoelectric accelerometer is used as the sensor element. Its electrical output
signal is first amplified and digitized.
The signal analysis is digital. The signal is filtered (HP, LP), optionally integrated
and the amplitude value is calculated, either as RMS or PEAK value. Finally, the
amplitude value is converted into a 4-20 mA current loop signal with a 16 bit DAC.
Piezo
GAIN
A
D
D
A
+
-
RXD
TXD
Signal
Analysis
4-20mA
KSI84xx
Parameter Set
- Range
- HP Filter, LP Filter
- Integrator
- RMS/Peak
- Average Filter
Port
ERROR
Detection
OVL
Detection
POWER
Supply

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Either the acceleration (without integration) or the velocity (with integration) of the
vibration can be measured.
In addition, proper sensor function and input signal are monitored. Defects or
overloads are signaled by an error current value.
Before delivery, the sensor is parameterized according to the type code selected by
the customer.
3 Type Selection
There are four different basic types, which differ in the measured quantity
(acceleration or velocity) and the amplitude mode (RMS or PEAK).
Sensor type
KSI84AR-xx
KSI84AP-xx
KSI84VR-xx
KSI84VP-xx
Quantity
Q
Acceleration
Velocity
Mode
M
RMS
PEAK
RMS
PEAK
Furthermore, the types differ in the measured frequency range (HP, LP) and in their
measuring range.
3.1 Frequency Range (HP, LP)
The used frequency range of a sensor type is described by the values HP and LP in
the type table.
HP is the -3 dB cutoff frequency of the high pass filter and determines the lower
cutoff frequency of the sensor.
LP is the -3 dB cutoff frequency of the low pass filter and determines the upper
cutoff frequency of the sensor.
All frequencies between the lower and upper cutoff frequency have an impact to the
measuring result.
Sensors measuring acceleration have a 2nd order IIR high pass and low pass filter
with a stopband attenuation of -40 dB/decade.
Frequency response