Related Manuals for MMF M68 Series
Summary of Contents for MMF M68 Series
- Page 1 Operator’s Manual Charge Amplifiers Series Metra Mess- und Frequenztechnik Radebeul Meissner Str. 58 - D-01445 Radebeul Phone +49-351-836 2191 Fax +49-351 836 2940 Email: Info@MMF.de Internet: www.MMF.de...
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Page 2: Table Of Contents
Contents 1. Application 2. Function and Operation 2.1. Introduction 2.2. Power Supply 2.3. Inputs 2.4. Amplifier 2.5. Filters 2.6. Integrators 2.7. Rack Mounting Cases for Model M68R1 3. Technical Data Appendix: Limited Warranty Declaration of Conformity “ICP” is a trade mark of PCB Piezotronics Inc. Jan. - Page 3 Fig. 1: Front view of Model M68D1 with control elements...
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Page 4: Application
1. Application The Signal Conditioners of M68 series are intended for connection of piezoelectric acceleration, force or pres- sure transducers. The input is suitable for sensors with ® charge output as well as for ICP compatible transduc- ers or microphones. -
Page 5: Function And Operation
2. Function and Operation 1. Introduction Fig. 2 shows the block diagram of Model M68 with its most important functional groups. supply J1 (ICPon/off) Frequency 0.1Hz Gain Gain Input Output Q/10 Q/10 High Low pass 1. Int. 2. Int. pass Compa- >5% rator... -
Page 6: Power Supply
90 % of full-scale modulation. It also indicates overload before the filter stages. Models M68D1, M68D3, and M68R1 have identical electronic circuits. 2. Power Supply External The Signal Conditioners M68 are powered by an exter- Supply nal DC voltage • Models M68D1 and M68D3 come with a mains plug adapter for 115/230 VAC. - Page 7 Also, remove the batteries if the unit is not in use for a longer period. Voltage All models of M68 series have an LED “BAT O.K.” Control indicating sufficient supply voltage. It lights up green, as long as the voltage is above 5 V. It works for battery operation as well as for external power supply.
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Page 8: Inputs
3. Inputs The Signal Conditioners M68 are designed for both sensors with charge output and with integrated imped- ® ance converters to ICP standard as well. You can switch from one to the other type of transducer by means of the slide switch next to the input socket. Both types use the same BNC input socket. - Page 9 This constant current must be fed into the measuring line and simultaneously separated from the following amplifier stages. The yellow LED “ICP ON” indicates the flow of constant current. ICP Transducer Signal Conditioner Integrated amplifier const coaxial cable, Piezo > 100 m ceramics Coupling capacitor Constant supply current...
- Page 10 positive overload Max. output voltage = supply voltage of 24 V constant current source Sensor bias voltage 5 .. 14 V (see data sheet) Min. output voltage = 0.5..1 V saturation voltage (see data sheet) negative overload Fig. 5: Dynamic range of ICP compatible transducers Switching Off In some cases it may be necessary to switch off the...
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Page 11: Amplifier
4. Amplifier The instruments of M68 Series have the following measuring ranges: Charge mode: 0.1 / 1 / 10 / 100 / 1000 mV/pC... -
Page 12: Filters
The instruments of M68 series have 6 internal low pass filters. The scale at the positions of the filter switch “LOW PASS” is shows the 3 dB limiting frequencies in kHz. - Page 13 3 dB Frequency 10 % Frequency 100 Hz 70 Hz 300 Hz 200 Hz 1 kHz 700 Hz 10 kHz 7 kHz 20 kHz 14 kHz 50 kHz 35 kHz The slope of the low pass filters is 40 dB per decade. 0 dB 180°...
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Page 14: Integrators
180° 0 dB 90° -20 dB -90° -40 dB -180° Fig. 7: Frequency and phase response of the high pass filter As the filters are located between the amplifier stages (see Fig. 2) the instrument does not become overloaded, even if the measured signal has higher spectral compo- nents outside the filter range. - Page 15 Relation The following calculations show how the output of the Between M68 (u ) corresponds to the three vibration quantities. Output Voltage The selected gain range of the M68 is G and the accel- erometer sensitivity (see transducer data sheet) is B and Vibration Quantity Vibration acceleration a (without integration):...
- Page 16 Max. modulation Modulation limits 1000 Fig. 8: Frequency response of the integrators 180° 90° -90° -180° 1000 Fig. 9: Phase response of the integrators Overload at In some cases signal components with high frequency Integrator and magnitude may overload the amplifier although no Input overload can be detected at the M68 output.
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Page 17: Rack Mounting Cases For Model M68R1
7. Rack Mounting Cases for Model M68R1 For the 19” unit M68R1 the following rack mounting cases are available: Model Channels Built-in power supply M68A6 M68A12 M68B6 M68B12 Fig. 10: Rack case M68A6 for 6 channels The rack mounting cases without internal power sup- plies Model M68A6 and M68A12 have an open rear side (see Fig. -
Page 18: Technical Data
The rack cases with internal power supply Models M68B6 and M68B12 supply the plugged-in modules via a backplane. They can be operated with both 115 VAC and 230 VAC without changing any settings. Replacing The fuse holder of the rack cases M68B6 and M68B12 the fuse with mains power supply is located inside the mains socket at the rear. -
Page 19: Appendix: Limited Warranty
5 .. 15 VDC External supply < 300 mA (M68D1, M68R1) < 1 A (M68D3) connector to DIN 45323 (M68D1 / M68D3) 4 pin frame connector (M68R1) 4 x “AA” size (LR6) Battery supply (only M68D1) > 10 h lifetime with alkaline cells Wide range input 85 .. -
Page 20: Declaration Of Conformity
Declaration of Conformity Products: Charge Amplifiers Models: M68D1, M68D3, M68R1 It is hereby certified that the above mentioned products comply with the demands pursuant to the following standards: • EN 50081-1 • EN 50082-1 • EN 61000-3 • EN 60950 Responsible for this declaration is the producer Metra Mess- und Frequenztechnik Meißner Str.
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