Specifications

7-1
Section 7. Grounding
Grounding the CR1000 and its peripheral devices and sensors is critical in all
applications. Proper grounding will ensure the maximum ESD (electrostatic
discharge) protection and higher measurement accuracy.
7.1 ESD Protection
ESD (electrostatic discharge) can originate from several sources. The most
common, and most destructive, are primary and secondary lightning strikes.
Primary lightning strikes hit the datalogger or sensors directly. Secondary
strikes induce a voltage in power lines or sensor wires.
The primary devices for protection against ESD are gas-discharge tubes
(GDT). All critical inputs and outputs on the CR1000 are protected with GDTs
or transient voltage suppression diodes. GDTs fire at 150 V to allow current to
be diverted to the earth ground lug. To be effective, the earth ground lug must
be properly connected to earth (chassis) ground. As shown in FIGURE 7.1-1,
th
e power ground and signal ground are independent lines until joined inside
the CR1000.