Campbell 21X Manual do Operador descarregar pdf (Página 158)

14.9 21X PqWER SUPPLIES

I

The 21X is

{vailable

with both

alkaline

batteries

(21X)

and lepd acid

batteries

(21XL).

The

difference b6tween

the 21X and 21XL is the

power

supplf base. Converting

from

a

21X to

21XL or

vics versa can be done by simply

purchasing

he

appropriate

base.

14.3.'1

21X ALKALINE

POWER

SUPPLY

The 21X utilizes I alkaline

D

cells.

Two screws

must

be

from the

front

panel

to

install

the see

Figure

14.3-1.

After battery

installation,

power

switch

on

the side of the

21X will the datalogger on and otf.

To

replace

tfe

batteries

without

losing the

datalogger

{rogram

and data: 1) do

not

turn

the

power

switcfr off,

2) connect

an

external battery

to the

12 voft, 3)

remove the

old batteries,

4)

replace

with new alkaline D

cell

batteries, and

5)

remove the external battery.

A fresh set

df

eight alkaline D cells

has 12.4

volts and a

/nominal rating of 7.5 amp-hours at

20oC.

The

{mp-hour

rating

decreases

with

temperature as

shown

in Table

14.3-1.

Datalogger

fnstruction

10

can be used to

monitor battpry

voltage.

Replace

the alkaline

cells

before the

21X battery voltage drops below

9.6 V.

TABLE

14.3-1.

Typical

Alkaline

Baftery

SBrvice and

Temperature

Temperatute

(oC)

o/o

ol2OoC

Service

20-5q

15

10

5

0

-10

-20

-30

100

98

94

90

86

70

50

30

SECTION

14. INSTALLATION AND

MAINTENANCE

14.3.2 21XL LEAD ACID BATTERY

POWER

SUPPLY

The 21XL

includes

a

'12Y,2.5

amp-hour

lead

acid battery,

a

AC transformer

(20V

DC), and

a

temperature compensated charging circuit

with

a

charge

indicating

diode.

An AC transformer

or solar

panel

should be connected

to

the

21XL

at alltimes.

The

charging

source

powers

the

21X while float

charging the

lead acid batteries.

The internal lead

acid battery

powers

the

datalogger

if the

charging source

is interrupted.

The 21XL lead

acid battery

specifications are

given

in Table

14.3-2.

The connector

from the

charging source can be

inserted into

the receptacle on the

side of the

21XL. A

transzorb

provides

transient

protection

to the charging

circuit.

A sustained

input

voltage in excess

of 40V

will

cause

the

transzorb to

limit

voltage.

Solar

panels

and

AC transformers should

be

supplied

with

a connector.

lf trying to use

a

charging source which has only two bare

leads

(no

connector), contact Campbell Scientific

for

identification

of the

proper

connector.

The red light

(LED)

on

the

21XL is on during

charging.

The

switch

turns

power

on and

off,

battery charging

still

occurs when the switch

is

off.

lf

the

voltage

of the lead acid batteries

drops below 11.76 volts before

recharging,

permanent

damage

to the lead acid cells

may

result.

CampbellScientific

does

not

warrant

batteries.

Monitor

the

power

supply using datalogger

Instruction 10.

Users are strongly

advised to

incorporate

this instruction into their data

acquisition

programs

to

keep track of the

state

of

the

power

supply.

lf

the system

voltage

level

consistently

decreases through

time, some

element(s) of the charging system

has failed.

Instruction

10 measures the

voltage at the

12V

port,

not the voltage

of the

lead acid battery.

External

power

sources

must be disconnected

lrom

the

21XL

in order to

measure the actual

lead

acid battery voltage.

dala is based on one

"D"

cell

ions of 50 mA current drain

ohm

load. As

the current

drain

the

percent

service

improves

for

14-3

1 2 ... 153 154 155 156 157 158 159 160 161 162 163 ... 190 191

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