eZ-Analyst
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Edit Menu 4-17
IEPE
(Integral
Electronics
Piezoelectric)
The Institute of Environmental Science and Technology adopted the term IEPE
(Integral Electronics Piezoelectric) to identify what had been commonly referred
to as ICP
®
(Integrated Circuit Piezoelectric). The two terms are synonymous;
however, ICP is registered by PCB Pizeotronics.
IEPE supportive analog channels have a 4mA bias current available for continuous
use by signal input transducers, as indicated in the following table:
Device
Channels that support IEPE
ZonicBook/618E
1 through 8
640e, 640u
1 through 4
650e, 650u
1 through 4
652u
1 through 10
655u
1 through 10
The bias current is sourced through the center conductor of the input channel
BNC connector and returns to the acquisition device [e.g., ZonicBook/618E, 640,
650, 652, 655 or WBK18] via the BNC’s outer conductor
The current source features an operating compliance of 24V and is protected in
regard to both short-circuit and overvoltage. Operating compliance refers to the
highest voltage that can be applied without change of the current source value.
In the absence of a transducer, the current source will output an open circuit
voltage of 30V. For applications that do not require bias, the current source can
be disconnected from the input by un-checking IEPE in the Input Channels tab on
a per-channel basis.
When the IEPE cell is checked for a channel, the current source is enabled, and
the input voltage is continuously monitored with level detection circuitry.
Recognition of a voltage greater than 25V (transducer open) or less than 1V
(transducer short) triggers a transducer fault condition for the affected channel.
This error is communicated to the user via a front panel LED and is also available
through a software status request at the end of an acquisition. When recognized,
an error is latched until the commencement of a new acquisition. Consequently,
even intermittent faults are detected and communicated. Detection of a fault
does not, however, alter the acquisition process or its data.
When the IEPE function is not available to a channel a dash appears in the IEPE
column for the associated channel.
