MMF M12 User manual

Instruction Manual
Manfred Weber
Metra Mess- und Frequenztechnik in Radebeul e.K.
Meissner Str. 58 - D- 1445 Radebeul / Germany
Phone [phone] Fax [phone]
Email: [e-mail] Internet: www.MMF.de
Universal
Vibration
Monitor
M12
Version C

Published by:
Manfred Weber
Metra Mess- und Frequenztechnik in Radebeul e.K.
Meißner Str. 58
D-0 445 Radebeul / Germany
Tel. [phone]
Fax [phone]
Email [e-mail]
Internet www.MMF.de
Notice: The latest version of this manual can be found at
http://www.mmf.de/produktliteratur.htm
© 20 7 Manfred Weber Metra Mess- und Frequenztechnik in Radebeul e.K.
May/ 7

Contents
. The M 2 at a Glance..................................................................................5
2. Purpose.......................................................................................................6
Measured Vibration Quantities.......................................................6
Outputs...........................................................................................6
Filters..............................................................................................6
LED Indicators...............................................................................6
3. Function......................................................................................................7
Sensor Input....................................................................................7
Amplifier.........................................................................................7
Filters..............................................................................................8
Integrators.......................................................................................8
RMS Rectification..........................................................................8
Peak-to-Peak Rectification..............................................................8
DC Outputs.....................................................................................8
4-20 mA Loop Output.....................................................................8
Alarm Relay....................................................................................8
Level Display..................................................................................9
Response time.................................................................................9
Self Test Functions........................................................................ 0
AC Output..................................................................................... 0
Overload Indication...................................................................... 0
Power Supply................................................................................ 0
Triple Insulation............................................................................ 0
4. Installation................................................................................................
4. . Preparing Measuring Points..........................................................................
Sensor Location............................................................................
ISO 08 6- ................................................................................. 2
4.2. Installation and Adjustment.......................................................................... 3
4.2. . Attachment............................................................................................ 3
Terminals...................................................................................... 4
4.2.2. Power Supply........................................................................................ 4
Power-on Alarm Delay.................................................................. 4
4.2.3. Sensor................................................................................................... 5
Sensor Input.................................................................................. 5
Sensitivity Adjustment.................................................................. 5
Sensor Status Indication................................................................ 5
Sensor Connection........................................................................ 7
Operation of Two M 2 Modules with One Sensor........................ 7
4.2.4. Selecting a Vibration Quantity.............................................................. 8
Dynamic Range of the Integrators................................................. 9
RMS / Peak-to-Peak..................................................................... 9
Response time............................................................................... 9
4.2.5. Selecting the Measuring Range.............................................................20
Overload Indication......................................................................20
4.2.6. Plug-in Filters.......................................................................................20

Slope.............................................................................................20
Factory Configuration...................................................................20
Replacing Filter Modules..............................................................2
4.2.7. Relay Output.........................................................................................22
Adjustments..................................................................................22
Connection of the Relay Output....................................................22
Self Test Function.........................................................................23
Sensor Monitoring........................................................................23
Contact Rating..............................................................................23
4.2.8. Current Loop 4-20 mA Output.............................................................23
Connection....................................................................................24
Insulation......................................................................................24
False Polarization.........................................................................24
4.2.9. DC Outputs...........................................................................................25
4.2. 0. AC Output...........................................................................................25
Filtering and Integration...............................................................25
Settings.........................................................................................25
Output Level.................................................................................27
Bandwidth.....................................................................................27
Connection....................................................................................27
4.3. Calibration....................................................................................................28
Factory Calibration.......................................................................28
Calibration Point...........................................................................28
Vibration Calibrator......................................................................28
Electrical Calibration....................................................................28
4.4. Vibration Level Display M 2DIS.................................................................29
Connection....................................................................................29
LED Backlighting.........................................................................29
Mounting......................................................................................30
Calibration....................................................................................30
5. Measuring Methods for Machine Vibration.............................................3
5. . Vibration Severity Measurement for Unbalance...........................................3
ISO 08 6- .................................................................................3
Measurement with the M 2..........................................................32
5.2. Vibration Measurement on Reciprocating Engines.......................................33
DIN/ISO 08 6-6.........................................................................33
Measurement with the M 2..........................................................34
5.3. Bearing Monitoring......................................................................................34
General.........................................................................................34
Crest Factor...................................................................................34
Diagnostic Coefficient..................................................................35
Measurement with the M 2..........................................................35
6. Technical Data..........................................................................................36
Appendix: Warranty
Declaration of CE Conformity

1.The M12 at a Glance
Front View:
AC Out-I Out+I Out
COM
+UsPK-PKRMS
-UsGNDInput
relay outputs
4-2 mA loop / AC output
RMS / peak-to-peak outputs
positive supply terminal
sensor input, signal ground
negative supply terminal
rear terminals
front terminals
N.C. N.O.
1
1
%
25
s %
LED bargraph display
for monitored quantity
and alarm threshold
Alarm OK OVL
LEDs for alarm,
sensor condition and overload
potentiometers for alarm delay
and alarm threshold
rear terminals
front terminals
Side View:
5
Adjustment of
transducer sensitivity
1 2 3 4 5 6 7 8 91
Function of the DIP switches
in their lower position
1: Sensor supply on
2: Range 1
3: Range 5
4: Range 25
5: Double integration (displacement)
6: Single integration (velocity)
7: Integration off (acceleration)
8: RMS monitoring
9: Peak-to-peak monitoring
1 : Alarm duration short

2.Purpose
The Universal Vibration Monitor is suitable for applications
where vibrations need to be monitored or measured. Typical
applications include condition monitoring of rotating machin-
ery to ISO 08 6 and bearing monitoring. The M 2 provides
information about the running condition of a machine.
Thereby it helps the maintenance engineer to predict wear in
time and to avoid unexpected breakdown. Thus the M 2 can
reduce cost caused by production loss and unnecessary re-
pairs. The M 2 can also be used for many tasks in process
and quality control.
Its flexible design makes it easy to adapt the M 2 for any
monitoring application. This can be of particular advantage if
no information about the vibration signal and its frequency
components is available before installation.
The M 2 provides standardized output signals for further pro-
cessing. A relay output for shut-off functions or alarm mes-
sages is also available.
Measured
Vibration
Quantities
The M 2 is designed for operation with an IEPE compatible
piezoelectric accelerometer. It can be used for measuring the
following quantities
• Vibration acceleration (without integration)
• Vibration velocity (single integration)
• Vibration displacement (with double integration)
For each vibration quantity among 3 measuring ranges can be
chosen.
Outputs The vibration signal is available at the following outputs:
• AC wide band output of amplified but unfiltered sensor
signal
• AC output of amplified, filtered and, if necessary, inte-
grated sensor signal
• DC output of true RMS for selected vibration quantity
• DC output of peak-to-peak value for selected vibration
quantity
• 4-20 mA current loop output of RMS or peak-to-peak
value for selected vibration quantity
Filters The use of replaceable filter modules makes the M 2 particu-
larly versatile. High pass and low pass frequencies can be se-
lected individually by means of an extensive range of avail-
able filter modules.
LED Indicators The following LED indicators can be found at the front panel:
• Alarm LED
• Sensor status LED
• Overload LED
• LED bar graph for monitored vibration quantity and
alarm threshold
6

3.Function
Figure : Block diagram
Sensor Input The M 2 requires for operation a piezoelectric accelerometer
with integrated electronics to IEPE standard. The instrument
is factory calibrated for standard industrial accelerometers
with 00 mV/g sensitivity, for example Models KS80 or
KS8 of Metra with protection grade IP67 and insulated case.
The constant current for the integrated sensor electronics is
supplied by the M 2 and can be activated by DIP switch .
Amplifier The amplifier with variable gain has over 50 kHz bandwidth.
At the side wall of the instrument a potentiometer for trans-
ducer sensitivity fine tuning can be found. The adjustable
range is 0 to 00 mV/g. The M 2 has 3 gain ranges which
can be selected by the DIP switches nos. 2, 3 and 4 at the side
wall as shown in the following table:
Vibration
acceleration
Vibration
velocity
Vibration
displacement
DIP 2 0 m/s² 0 mm/s 00 µm
DIP 3 50 m/s² 50 mm/s 500 µm
DIP 4 250 m/s² 250 mm/s 2500 µm
7
IEPE
Supply
Integrator
1
Highpass
2 poles
Plug-in
module
~
~
pk-pk
rms
AC Output
Integrator
2
pk-pk
rms
Transducer
Monitoring
Opto
Coupler
U
I
Loop Output
4-2 mA
Alarm
Threshold
Alarm
Delay
Alarm
Hold
Alarm
Relay Relay
Output
Alarm Threshold
(Front)
Dalay
(Front)
2/8 s
DC Output
rms
Bar
graph
Level
Alarm Threshold
Sensor OK
Alarm
Transd.
Fault
Overload LED
Overload
Comparator
DC Output
pk-pk
V1
V2
V3
ICP
a
v
d
Transducer sensitivity
Output
Driver
Amplifier
J1
filtered
unfiltered
1
2
3
4
5
6
7
8
9
1
Input
Stage
Lowpass
4 poles
Plug-in
module

Filters The M 2 contains separate high pass and low pass filters.
These filters are designed as plug-in modules. Thus they can
be replaced on site if necessary. The high pass filter has two
poles with an attenuation of about 40 dB/decade. The low
pass filter has four poles with about 70 dB/decade attenua-
tion.
Integrators For measuring vibration acceleration the M 2 is used without
integrators. When vibration velocity is measured, one integra-
tor is in the signal path. Vibration displacement requires dou-
ble integration. The integrators are switched on or off by the
DIP switches nos. 5 to 7.
RMS
Rectification
The instrument measures the true RMS value which ensures
high accuracy independently of the signal shape. The RMS
output is available via a 0 to 0 VDC output for external pro-
cessing. The RMS refresh rate is approx. value / second.
Peak-to-Peak
Rectification
Additionally, the peak-to-peak value of the selected vibration
quantity is measured. True peak-to-peak rectification ensures
high accuracy independently of the signal shape. The absolute
values of the highest positive and the lowest negative sample
of the last 00 ms are added. The peak-to-peak output is
available via a 0 to 0 VDC output for external processing.
The refresh rate is 00 ms.
DC Outputs Both RMS and peak-to-peak values are available simultane-
ously at two separate outputs. Only one of these signals, how-
ever, can be used for controlling the relay and the 4-20 mA
output. The monitoring mode is selected by the DIP switches
no. 8 (RMS) and 9 (Peak-to-peak).
4-20 mA Loop
Output
The RMS or peak-to-peak value of the selected vibration
quantity is available as 4-20 mA current loop signal. This cur-
rent loop output allows the transmission of analog signals
over long distances with inexpensive cables. At the destina-
tion the pre-processed vibration signal can be fed into PLCs,
panel meters, recorders or other 4-20 mA equipment.
A side effect of long distance signal transmission can be
ground loops. The accuracy of the M 2 will not be affected
by this phenomenon since the current loop output is optically
insulated from the rest of the circuit.
Alarm Relay In addition to its analog outputs, the M 2 features a relay out-
put which can be used to trigger external events when the ad-
justed threshold is exceeded. Possible devices to be connected
are, for instance, contactors, alarm signals or binary inputs of
a PLC. The relay output has a potential-free “Form C” con-
tact. An “Alarm” LED indicates that the relay has responded.
Both alarm threshold and delay (td) can be adjusted at the
front panel. The adjustable delay range is 0 to 25 seconds.
The relay hold time can be selected between two and eight
seconds by means of DIP switch no. 0.
Figure 2 illustrates how the alarm management works.
8

t
Alarm
threshold
Alarm on
Alarm off
tdt
td
12
3
4
7
6
5
th
on
Figure 2: Alarm management
The upper curve of the diagram represents a typical vibration
signal over time. It can be RMS or peak-to-peak signals. The
lower curve shows the relay response.
At point  the adjusted threshold was exceeded. Now the de-
lay time td starts. It can be adjusted at the front panel between
0 and 25 s. Since the signal drops below the threshold at point
 before the delay time was over, no alarm will be tripped at
point . By selecting an appropriate delay time is guaranteed
that no alarm will be tripped by short signal transients. They
may occur during machine start up or under the influence of a
short mechanical shock pulse. At point  the alarm threshold
is exceeded again and the delay time starts for the second
time. Now an alarm will be tripped since after td at point 
the alarm threshold is still exceeded. The relay remains active
until the vibration level drops below the limit at . Now the
alarm hold time th begins. It can be selected by DIP switch no.
0 between 2 and 0 seconds. When this hold time is over at
point  the relay switches back. The purpose of a pre-se-
lected hold time is to ensure save switching of external com-
ponents.
Level Display The bar graph display at the front panel has two functions. On
one hand, it shows the current RMS or peak-to-peak value of
the selected vibration quantity between 0 and 00 % of the
full-scale value. On the other, it shows the relay threshold
which can be adjusted by the potentiometer below.
The LED display gives comprehensible information about the
current status of the vibration monitor.
Please note also the optionally available display module
M 2DIS (see section 4.4).
Response time For time-critical monitoring applications the peak-to-peak
value is recommended because of its higher refresh rate at the
analog outputs and the relay output.
9

Self Test
Functions
It is expected that monitoring equipment should have a very
high reliability. Unnoticed faults need to be avoided and false
alarms as well. Maximum reliability of the M 2 is guaran-
teed by a two-stage self-test circuitry:
Monitoring of sensor bias voltage recognizes defective ac-
celerometers and cables. When an open loop at the sensor in-
put is detected, the “OK” LED is switched off. A short circuit
at the input is indicated by a flashing “OK” LED. In both
cases the relay will switch to alarm position whereas the
“Alarm” LED remains dark.
Power supply failure also causes the relay contact to switch
into the alarm position.
AC Output In addition to the DC outputs, the M 2 also provides a “raw”
vibration signal. By means of Jumper a selection can be
made between the buffered and unfiltered sensor signal or the
amplified, filtered and, if selected, integrated signal (see Fig-
ure ).
In the first case, the AC output provides the sensor signal with
a bandwidth of over 50 kHz. Please note that most standard
accelerometers have their resonance at 20 to 30 kHz.
In the second case, the AC signal is pre-processed in accor-
dance with the selected vibration quantity and the inserted fil-
ters.
Overload
Indication
An LED “OVL” is located at the front panel. It signals an
overload condition before the filters, after the amplifier and
after the integrators. If the LED starts flashing, the measuring
signal will still be undistorted but it reaches its limits at
± 0 V.
Power Supply The M 2 needs for operation a DC supply voltage of 2 to
28 V. Its current consumption is between 80 and 200 mA. The
lower the supply voltage, the higher the supply current.
Triple Insulation Optimum protection against grounding problems is achieved
by triple insulation between supply voltage, signal path and
current loop output.
Power
Supply
4-2 mA
Output
Signal Path
Figure 3: Triple Insulation
0