Campbell 21X Manuale dell'Operatore Scaricare il pdf (Pagina 159)

SECTION 14. INSTALLATION

AND

MAINTENANCE

TABLE

14.3-2.

21XL

Battery

and

AC

Transf

ormer

Specif ications

Lead Acid Battery

Battery Type

Float

Life

@ 25oC

Capacity

Shelf

Life,

fullcharge

Charge

Time

(AC

Source)

AC Transformer

Input:

lsolated Output:

Gates #810-0011X

8

years

minimum

2.5

amp-hour

Check twice

yearly

40 hr full

charge,

2O

hr 95o/" charge

120V AC, 60 Hz

20V

DC @ 350 mA

max.

There

are

inherent

hazards

associated with

the

use

of

sealed lead

acid

batteries. Under

normal

operation,

lead

acid

batteries

generate

a small

amount of hydrogen

gas.

This

gaseous

by-

product

is

generally

insignificant

because the

hydrogen

dissipates naturally

before

build-up

to

an explosive

level

(4"/")

occurs. However, if the

batteries are shorted

or overcharging

takes

place,

hydrogen

gas

may be

generated

at a

rate

sufficient

to

create ahazard.

Campbell

Scientific

makes

the following

recommendations:

1 . A 21X equipped

with standard

lead

acid

batteries should NEVER

be used in

applications

requiring

INTRINSICALLY

SAFE

equipment.

2.

A

lead acid

battery

should not be housed in

a

gas-tight

enclosure.

14.4

SOLAR

PANELS

Auxiliary

photovoltaic power

sources,

such

as

Solarex

Models

MSXS,

MSX10,

and MSX18

Solar Panels

may

be used

to maintain

charge

on lead acid

batteries.

TABLE

14.4-1.

MSX5

and MSX10

Solar

Panel

Specifications

MSX5 MSX10

MSX18

Typical

Peak

Power

4.2

8.9

18.6

(Watts)

Current @

Peak

(Amps)

Amp

Hrs/week

.27 .59 1.06

6.4 14.4 26.4

14-4

NOTE:

Specifications assume 1 kWm2

illumination at

a

panel

celltemperature

of

25oC. Individual

panel

performance

may

vary

as

much as 107o.

When

selecting a solar

panel,

a rule-of-thumb

that

on a stormy

overcast

day the

panel

should

provide

enough charge to meet

the system

current drain

(assume

1Oo/"

of average annual

global

radiation,

kwm2).

Specific site

information,

if

available,

could

strongly i

the solar

panel

selection.

For

example, local

etfects such

as

mountain shadows, fog

from

valley

inversion, snow, ice, leaves,

birds, etc.

shading the

panel

should be

considered.

Guidelines are available lrom the Solarex

Corporation

for solar

panel

selection called

"DESIGN

AIDS FOR SMALL PV POWER

SYSTEMS". lt

provides

a method for

calculating

solar

panel

size based on

general

site location

and

system

power

requirements.

lf

you

need help in determining

your

system

power

requirements contact Campbell

Scientif ic's Marketing Department.

14.5 DIRECT

BATTERY CONNECTION

TO THE 21X

Any 10 to 13V DC supply may be connected

to

the 12V and

ground

terminals on the 21X. Be

careful not

to short

the leads together when

connecting them

to

the datalogger.

A

blocking diode

prevents

the external battery

from charging

the

internal

alkaline batteries.

14.6

VEHICLE POWER

SUPPLY

CONNECTIONS

When

a vehicle's starting

motor

is engaged,

the

supply voltage

drops

considerably

below the

nominal 12 volts. lf the 21X is

connected

directly to the vehicle's

power

supply, the 21X's

batteries

are also

pulled

down causing an E08

error

each time the

vehicle is

started.

Avoid

problem

by

placing

a diode

(1N4001)

and a 3

ohm, 5 watt resistor

in

series with the

positive

lead

going

to the

+12V terminal

(Figure

14.6-1).

The diode

allows the

vehicle

to

power

the 21X

without

the datalogger attempting to charge

the

vehicle.

The

ground

lead should

be

16

AWG or

larger

to reduce

the

potential

for

ground

reference

errors

in the measurements.

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