4
2.2 Softline Cable
Special high temperature low-noise, shielded cable 2-wire cable assembly is required with charge mode
sensors for applications up to 500°F to connect the transducer to the charge amp. When additional
mechanical protection is required a stainless steel armor can be used.
The shield acts as a Faraday cage to reduce electrical noise from corrupting the signals, and minimizes
capacitively coupled noise from other electrical sources.
Standard, two-wire, or coaxial cable, when flexed, generates a charge between the conductors. This is referred
to as triboelectric noise and cannot be distinguished from the sensor's charge output. Low-noise cables have a
special graphite lubricant between the dielectric and the braided shield, which minimizes the triboelectric effect
and improves the quality of the sensor's charge output signal.
When using separate cables connect the cable to the accelerometer. A small amount of thread-locking
compound placed on the connector prior to attachment helps secure the cable during testing. In harsh
environments, the connection can be sealed with silicone rubber, O-rings, and flexible heat-shrink tubing.
2.3 Integral Hardline Cable
For extremely high temperature (>500°F) charge mode applications use mineral insulated (MI) hardline. Keep
cable clean to maintain insulation resistance and good low-frequency response
2.4 Hardline Connection Type
2.4.1 PCB / Lemo type connector
The Lemo connector is PCA.0S.302.CLAC42 that is specially adapted for use with hardline cable. The
connector is a self-latching system that allows the connector to be mated by simply pushing the plug axially into
the socket. When required the connector is disengage by a single axial pull on the outer release sleeve.
2.4.2 High Temperature 2
–pin 7/16-27 UNS connector
This connector is a Model GP, 2 Pin Jack, 7/16-27 thread. The connector is welded to the hardline to provide a
high temperature, hermetic connection. The GP connector uses a threaded connction to mate with a GN or ET
2-Socket plug and torqued to 5 ft*lbs +/- 1 ft*lb
2.5 In Line Differential Charge Amplifier
The differential in line charge amplifier is purchased separately
A conventional method for conditioning the high-impedance signal generated by a charge output sensor is to
use a differential 422 series in-line charge amplifiers operate from an ICP ® signal conditioner. The unit
employs a high gain amplifier to perform the impedance transformation. The charge output of the transducers
may be scaled in terms of acceleration, pressure or force. The output is then mV/g, mV/psi or mV/lb,
respectively.
Summary of Contents for EX619A11
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