Section 7. Installation
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
Schematic of
Grounds
(p. 107),
signal grounds and power grounds have independent paths to the
earth-ground lug.
Communication ports are another path for transients. You should provide
communication paths, such as telephone or short-haul modem lines, with spark-
gap protection. Spark-gap protection is usually an option with these products, so
request it when ordering. Spark gaps must be connected to either the earth ground
lug, the enclosure ground, or to the earth (chassis) ground.
A good earth (chassis) ground will minimize damage to the datalogger and
sensors by providing a low-resistance path around the system to a point of low
potential. Campbell Scientific recommends that all dataloggers be earth (chassis)
grounded. All components of the system (dataloggers, sensors, external power
supplies, mounts, housings, etc.) should be referenced to one common earth
(chassis) ground.
In the field, at a minimum, a proper earth ground will consist of a 6 to 8 foot
copper-sheathed grounding rod driven into the earth and connected to the large
brass ground lug on the wiring panel with a 12 AWG wire. In low-conductive
substrates, such as sand, very dry soil, ice, or rock, a single ground rod will
probably not provide an adequate earth ground. For these situations, search for
published literature on lightning protection or contact a qualified lightning-
protection consultant.
In vehicle applications, the earth ground lug should be firmly attached to the
vehicle chassis with 12 AWG wire or larger.
In laboratory applications, locating a stable earth ground is challenging, but still
necessary. In older buildings, new Vac receptacles on older Vac wiring may
indicate that a safety ground exists when, in fact, the socket is not grounded. If a
safety ground does exist, good practice dictates the verification that it carries no
current. If the integrity of the Vac power ground is in doubt, also ground the
system through the building plumbing, or use another verified connection to earth
ground.
106
Summary of Contents for CR1000
Page 2: ......
Page 4: ......
Page 6: ......
Page 32: ......
Page 36: ......
Page 38: ......
Page 40: ......
Page 60: ...Section 4 System Quickstart Figure 16 PC200W View Line Graph 60 ...
Page 96: ......
Page 98: ...98 ...
Page 302: ......
Page 453: ...Section 8 Operation Figure 115 Using the Keyboard Display 453 ...
Page 456: ...Section 8 Operation Figure 118 Real Time Custom 456 ...
Page 457: ...Section 8 Operation 8 8 1 3 Final Memory Tables Figure 119 Final Memory Tables 457 ...
Page 458: ...Section 8 Operation 8 8 2 Run Stop Program Figure 120 Run Stop Program 458 ...
Page 460: ...Section 8 Operation Figure 122 File Edit 460 ...
Page 461: ...Section 8 Operation 8 8 4 PCCard Memory Card Display Figure 123 PCCard CF Card Display 461 ...
Page 478: ......
Page 506: ......
Page 536: ......
Page 636: ......
Page 642: ......
Page 644: ......
Page 676: ......
Page 677: ......