Charge amplifier ZET 440

Charge amplifier ZET 440 for piezoelectric detectors is intended for:

  • amplification and conversion of output signals of primary piezoelectric transducers with charge output;
  • amplification and conversion of output signals of primary transducers with the IEPE type in-built electronics to voltage;
  • gain ratios: 1, 10, 100;
  • LPF: 0.1, 1, 10 Hz

POR (price on request)

The ZET 440 preamplifier is used in vibration detector calibration system to connect AP10 reference acceleration meter to the ZET 017 FFT spectrum analyzer. In combination with vibration measuring converters, the amplifiers can be used in technical diagnostics and monitoring systems implemented in various industries for measuring vibration and shock accelerations as well as in laboratory and scientific studies.

The ZET 440 amplifier allows to connect acceleration meters with charge output or of IEPE standard to FFT spectrum analyzers as well as to ADC and DAC converters. It also allows to connect the BC 311 sonic detectors to the ZET 017 FFT spectrum analyzer.

Specifications

of the ZET 440 Charge Amplifiers

Technical Specifications
Number of channels 1
“Charge” Input
Socket type BNC
Charge gain 1 mV/pC 10 mV/pC 100 mV/pC
Maximum input charge (peak) at GR=1, min. 104 pC
Operating frequency band with -3 dB attenuation at the boundaries and non-linear distortion coefficient below 10%:
within the output voltages range not more than 2.5 V (peak) 0.1 ~ 100 000 Hz
within the output voltages range not more than 5 V (peak) 0.1 ~ 50 000 Hz
within the output voltages range not more than 10 V (peak) 0.2 ~ 30 000 Hz
RMS of noise reduced to the input in “Charge” mode with sensor capacity 1 nF within 0.1 ~ 20 kHz frequency band (at gain 1 mV/pC), max. 0.04 pC
“IEPE” Input
Socket type BNC
Voltage gain 1 10 100
Maximum input voltage (peak) at GR=1, min. 10 V
Operating frequency band with -3 dB attenuation at the boundaries and non-linear distortion coefficient below 10%:
within the output voltages range not more than 2.5 V (peak) 0.1 ~ 100 000 Hz
within the output voltages range not more than 5 V (peak) 0.1 ~ 50 000 Hz
within the output voltages range not more than 10 V (peak) 0.2 ~ 30 000 Hz
RMS of noise reduced to the input in “IEPE” mode within 0.1 ~ 30 kHz frequency band, max. 20 µV
General Specifications
Main permissible relative accuracy limits for setting the gain at 1 kHz frequency at normal conditions ±0.6 % ±0.6 % ±1.2 %
Additional permissible accuracy limits for setting the gain within 0 ~ 40°C temperature range 0.5 %
Amplitude-frequency characteristics unevenness within 3 to 20,000 Hz band ±0.5 %
Cutoff frequencies of the in-built LPFs with at least 40 dB/decade amplitude-frequency characteristics and -3 dB attenuation 0.1 Hz 1 Hz 10 Hz
Output socket type BNC
Maximum output voltage (peak), min. ±10 V
Output resistance (for load current not more than 10 mA), max. 50 Ohm
Feed mode of sensors with IEPE  type in-built amplifier:
voltage
current
27 ± 3 V
3 ± 1 mA
Galvanic separation
resistance, min. 0.3 MOhm
permissible in-phase voltage, max. 260 V
Operating mode setup duration, max. 20 sec
Continuous operation time, max. 8 h
External DC power supply 12±1 V
Consumed current, max. 230 mA

Flow Diagram

of the ZET 440 Charge Amplifiers

Block diagram of the amplifier

The charge output vibration sensors are connected to “Charge” input, while IEPE standard acceleration meters are connected to IEPE input. Signal from the sensor passes through the high-pass filter with the cut-off frequency of 0.1, 1.0, or 10.0 Hz, then through the amplifier with 1, 10, or 100 gain, and then through the pseudo-galvanic separation, the signal is fed to the ZET 440 output. The input of the amplifier (“Charge” or “IEPE”) to which the vibration sensor is connected to, is determined automatically. Gain (sensitivity, amplifier conversion coefficient) and high-pass filter cut-off frequencies are set in the ZETLAB Device Manager Software.

Setup and Operation Principle

of the ZET 440 Charge Amplifiers

The amplifier operation principle is based on conversion of signals received from the primary transducers into low-impedance voltage signal. The amplifier may operate in charge amplification mode or voltage amplification mode, when in combination with IEPE type in-built amplifier.

To ensure operation with sensors having different conversion ratios, the amplifier provides the possibility of changing (normalization) the gain to produce adapted value of the output voltage. Availability of the in-build high-pass (HPF) and low-pass (LPF) filters makes it possible to select an optimum bandwidth. The amplifier allows to ensure indication of a connected input channel, set gain ratio, and high-pass filter selected for the measurement.

When charge output sensors are connected to the FFT spectrum analyzer using the charge amplifier ZET 440, the measurement channel requires some settings to be adjusted. Set gain ratio of ×10. on the charge amplifier ZET 440 “Settings” tab.

Adjusting the parameters of the charge amplifiers

Then go to settings of the FFT analyzer channel to which the ZET 440 charge amplifier is connected to, and in the “Measuring channel” tab with the channel properties, set the sensitivity level of the connected sensor in accordance with its certificate.

device Manager

Adjustment of the measuring channel

Caution

The ZET 440 amplifier’s charge gain is 1 mC/pC. Therefore, the sensitivity in pC/Pa equals to the sensitivity in mV/Pa when connecting via the ZET 440 amplifier. Thus, when a sonic detector is connected to the FFT spectrum analyzer through the ZET 440 amplifier, and the sonic analyzer sensitivity according to its certificate is 0.44 pC/Pa, and then enter 0.00044 V/Pa value in the “Sensitivity, V/unit” field.

The amplifier is designed as a portable mono-block unit and includes the following functional units: charge amplifier, voltage amplifier, low-pass filters, high-pass filters, and micro controller. The amplifier is powered by an external 12V DC power unit.

Special features

of ZET 440 charge amplifiers

As amplifiers for piezoceramic sensors one can use charge amplifiers or voltage amplifiers.

Voltage amplifiers have input impedance within the range of  10  kOhm – 1 mOhm.
ZETLAB products list supporting the above mentioned amplifiers:

Major drawback of these amplifiers is the necessity to repeatedly set the sensitivity of the sensor connected in the case of performing cable change (cable capacitance should be taken into consideration).

For charge amplifier ZET 440 the capacitance of cable and sensor are of no importance since the charge amplifier has calibration capacitor, which considerably simplifies the operation process.

Basic Configuration

of the ZET 440 Charge Amplifiers

Contents of delivery

Charge amplifier ZET 440 scope of supply includes:

  • preamplifier ZET 440;
  • cable Defender USB 2.0 A→B (length: 1,8 m);
    2 filters (USB04-06 PRO);
  • power supply module 220V →12V;
  • cable BNC-BNC (length: 0,6 m);
  • plug 50 Ohm.

POR (price on request)

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