Kipp&Zonen BSRN Scientific Solar Monitoring System - Manual (Page 40)

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A num ber of dataloggers are capable of withstanding harsh environm ents, including hot and
cold tem peratures and high relative hum idity. Such data collecting platform s should be considered
as an alternative to transm itting sm all analog signals through long cables back to a central
facility. Once the data is collected it can be transferred m uch m ore reliably as a digital signal.
(3) All cables that run along the ground should be buried to a depth where they will not norm ally
be disturbed by routine m aintenance operations. Cables not specifically capable of withstanding
burial should be placed in conduits. This increases the overall neatness of the site and reduces
the danger of personnel being injured or the cable being accidentally pulled from the instrum ent
when overly strained. When effort is being expended to place cables underground, extra capacity
for future expansion should be considered.
(4) Signal cables should be run through separate conduits from electrical power cables whenever
possible. Cables should cross at right angles to reduce electrical interference. W hen such
arrangem ents are im practical, specially shielded cables should be used.
(5) At rem ote locations, secondary signal processing and serial or satellite com m unications should
be considered to transfer data to a perm anent storage device. In the design of such a system ,
the potential for com m unication failures m ust be considered in the overall plan.
Cabling between the instrum ent and the data acquisition system should be carefully grounded and
protected against lightning. Figure 3.4 gives a general illustration on how the grounding and lightning
protection should be placed within the instrum ent/cable/acquisition system configuration.
W henever a system is wired, care m ust be taken to accurately m ap both the physical location of the
cables (especially if underground) and the connections running from the instrum ents through the junction
boxes to the data acquisition system .
3.5.3.2 Electrical Cable
Electricity should be available at the location of the sensors, both for the operation of the instrum ents
and for use in the m aintenance of the observation platform . Separate circuits for each set of instrum ents
is desirable, but not always practical. Whenever redundant instrum entation is used, it should be operated
on separate electrical circuits. All electrical wiring should m eet or exceed local electrical codes. The
local electrical utility, an electrical engineer or qualified electrician should be able to provide inform ation
on local electrical regulations and provide an estim ate of the electrical consum ption of the site.
Just as in the case of the signal cables, all electrical cables should be buried or securely fastened to
the instrum ent m ounting platform s. Furtherm ore, for safety, switches or circuit breakers should be installed
close to the equipm ent for easy servicing.
The quality of power supplied to the instrum ents should be the sam e as described in Section 3.4.2.