Table of Contents
Summary of Contents for MMF M72A1
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Page 1: Instruction Manual
Instruction Manual Charge / IEPE Conditioners M72 Series Manfred Weber Metra Mess- und Frequenztechnik in Radebeul e.K. Meißner Str. 58 - D-01445 Radebeul Phone +49-351-836 2191 Fax +49-351-836 2940 Email: Info@MMF.de Internet: www.MMF.de... - Page 2 The latest version of this document can be downloaded from: http://www.mmf.de/product_literature.htm © Manfred Weber Metra Mess- und Frequenztechnik in Radebeul e.K. Jan/ 17...
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Page 3: Table Of Contents
Contents 1. Application..........................3 Function and Operation......................4 Power Supply and Mass......................5 3.1. Grounding Concept......................5 3.2. External Power Supply......................5 3.3. Sources of Errors.......................5 3.3.1. Avoiding Ground Loops....................5 3.3.2. Low-Frequency Noise....................6 4. Inputs............................6 4.1. Charge Input........................6 4.2. IEPE Input.........................7 4.2.1. Switching Off the IEPE Power Supply...............8 5. - Page 4 Figure 1: M72A1 front panel Figure 2: M72A1 rear panel The letter “x” in this manual stands for the channel number of the versions M72A1, M72B1, M72A3 and M72B3.
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Page 5: Application
The instruments all have a robust aluminum housing making them suitable for work in the labo - ratory as well as under field conditions. The following model variants are available: Type Channels Sensitivity Standardization Level Meter TEDS M72A1 M72A3 M72B1 M72B3 Transducer Electronic Data Sheet... -
Page 6: Function And Operation
2. Function and Operation Figure 3 illustrates the most important functional groups of M72 in a block diagram. IEPE TEDS* supply IEPE on/off Read TEDS L.P. frequency Gain 0,1Hz Gain Input Output 0,1...1 Q/10 Q/10 1. Int. 2. Int. High pass Low pass Sensitivity* 100 kHz... -
Page 7: Power Supply And Mass
3. Power Supply and Mass 3.1. Grounding Concept The inputs and outputs of the signal conditioners are single ended, i.e. asymmetrical. The signal ground is connected to the outer conductor of the input and output sockets. The instrument housing is internally connected to ground. The power supply is signal-referenced, i.e. -
Page 8: Low-Frequency Noise
3.3.2. Low-Frequency Noise When the M72 is used with high gain and with the lower frequency limit of 0.1 Hz (high pass off) it may be sensitive to temperature transients. Even draft may result in output voltage fluctu- ation of some hundred millivolts at frequencies around 0.1 Hz. To reach thermal balance a warm-up time of some minutes is recommended before measurement. -
Page 9: Iepe Input
4.2. IEPE Input IEPE stands for "Integrated Electronics Piezo Electric". It has been established as the industrial ® standard for piezoelectric transducers. Other brand names for the same principle are ICP ® ® ® Isotron , Deltatron , Piezotron etc. The integrated sensor circuit transforms the charge signal of the piezo-ceramics, with its very high impedance and high EMI sensitivity, into a voltage sig - nal with low impedance. -
Page 10: Switching Off The Iepe Power Supply
The M72 uses the bias voltage for an IEPE functional check. Sensor errors are indicated as fol- lows: • quick flashing (ca. 4 Hz) of white LED: IEPE bias voltage < 1 V → short circuit in the sensor cable or sensor •... -
Page 11: Transducer Sensitivity (M72Ax / M72S1)
6. Transducer Sensitivity (M72Ax / M72S1) The output voltage of the M72Ax and M72S1 instruments can be scaled to result in a decimal ratio between the output voltage and the mechanical measurement quantities, for example 100 mV/ms or 1 V/Pa. By this means a measuring chain will always yield the same output voltage per mechanical unit, independently of the sensor type. -
Page 12: Level Indicators
7. Level Indicators The red LED “Overload” warns of signal clipping by high magnitudes. The indicator switches on at around 9 V peak voltage. At 9 V the output signal is still without distortion, however, it is close to the limit. The overload detector monitors the signal level at both the output and before the filters and inte - grators (see Figure 3). -
Page 13: High Pass Filter
8.2. High Pass Filter The M72 Signal Conditioners have a high pass filter with a lower limiting frequency of 3 Hz (-3dB). This eliminates low frequency noise which may otherwise occur with piezoelectric com- pression accelerometers under the influence of temperature transients (see Chapter 3.3.2). The second-order Butterworth filter has a slope of 40 dB / decade. - Page 14 The above equations apply to IEPE compatible accelerometers. Accelerometers with charge output are calculated in the same way with charge amplification G in mV/pC and the charge transfer factor B the transducers in pC/ms Example: With an accelerometer which has a sensitivity of B = 5 pC/ms , the velocity should be measured.
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Page 15: Keypad Lock
9. Keypad Lock To protect the instrument from unwanted or unauthorized operation, the keypad lock can be ac - tivated. To activate the keypad lock, hold down the “Input” button for 5 seconds when switching on the power supply voltage. Now, the instrument will no longer respond to the press of a but- ton. -
Page 16: Control Via Usb (M72R1 / M72S1)
11. Control via USB (M72R1 / M72S1) 11.1. Rack M72R8 and M72S8 The 19” rack enclosure can house up to eight M72R1 or M72S1 modules. The power supply is fed through the 9 pin D-Sub socket at the back of the amplifier modules (Figure 9). This socket also provides a serial RS-232 interface for communication with the rack enclosure. -
Page 17: Usb Interface
The first time you connect the rack casing to a PC you will be asked to install the device driver. The driver data file “MMF_VCP.zip” is located on the internet site http://www.mmf.de/software_download.htm#m72. Unzip and save both of the enclosed files to a directory on your computer. This directory will need to be entered when windows asks you for the device driver. -
Page 18: Interface Commands
11.3. Interface Commands All commands are structured as follows: #RMx..x The commands always begin with a hash symbol followed by the address (R) of the rack enclo- sure (0 to F). Next the address of the module (M) appears at its location in the rack enclosure. The address of the left module is 0 and the right module 7. - Page 19 #RMLl: select low pass l: 0: 0.1 kHz; 1: 1 kHz; 2: 10 kHz; 3: 50 kHz command acknowledgment: /a<CR> error at invalid parameters: /n<CR> Send example: #B5L3 (50 kHz) #RMO: overload condition (from version 001.005) Answer: no overload since last #O command at least one overload occurred since last #O command #RMSsssss: enter transducer sensitivity s: sensor sensitivity, 4 digits with the decimal point after 1...
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Page 20: Setup Tool For M72R8 / M72S8 Rack Cases
The program is compatible with Windows XP, Vista, 7, 8 and 10. Please download the zip compressed file m72x8.zip from our web page http://mmf.de/software_download.htm#m72 and unzip it on your PC. In the extracted folder start setup.exe and follow the instructions. You may change the installation folders but in most cases the default folders can be used. - Page 21 Figure 12: Program window with loaded settings Figure 12 shows the program window with the settings for eight modules. The eight channels of the addressed rack case are listed in rows. In the column Input you can select the input type. The types Charge, IEPE and Voltage are available.
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Page 22: Technical Data
12. Technical Data Charge, AC voltage and IEPE Measuring Inputs BNC socket, single-ended 3.5 to 4.5 mA constant current, compliance voltage >24 V, IEPE Sensor Supply switchable, IEPE function check with LED IEPE 1451.4, Template No. 25 for accelerometers and force trans- TEDS Support* ducers, with and without transfer function, Templates 27 and 28 for measuring microphones,... - Page 23 Warm-up Time Operating Temperature -10 to 55 °C, 95 % relative humidity, no condensation Dimensions 105 x 43 x 95 mm³ (M72A1) 105 x 37 x 95 mm³ (M72B1) (B x H x T) 105 x 104 x 95 mm³ (M72A3) 105 x 78 x 95 mm³...
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Page 24: Limited Warranty
The repaired or replaced product will be sent back at Metra’s expense. Declaration of Conformity According to EMC Directive 2014/30/EC Product: Charge/IEPE Conditioners Type: M72A1/M72B1/M72B1/M72B3/M72R1/M72S1/M72R8/M72S8 It is hereby certified that the above listed products comply with the demands pursuant to the following standards: DIN EN 61326-1: 2013...
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