Piezoelectric CCLD / IEPE Accelerometers
CCLD accelerometers are PE charge accelerometers (also refereed to as IEPE accelerometers) with integral preamplifiers that have output signals in the form of low impedance voltage output. Most Brüel & Kjær CCCLD accelerometers are hermetically sealed to protect against environmental contamination, they have low susceptibility to radio frequency, electromagnetic radiation and low a impedance output due to the built-in amplifier. This allows the use of inexpensive, and long, coaxial cables.
What are CCLD Accelerometers?
CCLD is a generic name identifying accelerometers (and is also refereed to as IEPE accelerometers) and CCLD Signal conditioning equipment that operate on a constant-current power supply and give output signals in the form of voltage modulation on the power supply line.
CCLD variants have built-in, low-noise preamplifiers that are made using thick-film technology. The preamplifiers comprise ASICs (application-specific integrated circuit) including a special reference voltage that ensures very stable bias voltage over the entire operating temperature range.
An obvious advantage of using CCLD equipment is that it allows you to use inexpensive cables.
The low-output impedance allows the use of long cables for connection between the accelerometer and the data acquisition hardware, ie. our Input DAQ Module (LAN-XI Type 3050).
Cables and Connectors for CCLD
For general, non-critical use, the following cables are recommended for use with CCLD variants:
- Single-screened Accelerometer Cable (AO-0463)
Flexible cable with coaxial connectors (male, 10 – 32 UNF), – 20, max. temperature: +80 °C (– 4 to +176 °F)
- Coaxial Accelerometer Cable (AO-0531)
Flexible cable with coaxial connectors (male, 10 – 32 UNF) to BNC (male) connectors, max. temperature: –20 to +80 °C (– 4 to +176 °F)
- Low-Noise Accelerometer Cable (AO-1382)
Double-screened cable with coaxial connectors (male, 10– 32 UNF), max. temperature: 250 °C (482 °F)
In order to distinguish individual accelerometers in a multichannel measurement setup, numbered cable markers (UA-1243) are available to fit cables that are 1.6 mm in diameter and coloured cable markers (UA-1244) are available to fit cables that are 1.9 to 2.2 mm in diameter.
Maximum Cable Length for CCLD
The maximum output voltage of a CCLD accelerometer when driving long cables depends on the supply current at which it is operating, and on the capacitive load due to the connecting cable.
The maximum cable length in metres (for distortion ≤1%) is given by:
L = 140000 x ls – 1 f x VoxCm
Is = supply current (mA)
f = frequency (kHz)
Vo = output voltage (Vpeak)
Cm = cable capacitance (pF/m)