Campbell Scientific CR10 CR10 Measurement and Control - Page 194

SECTION

14.

INSTALLATION AND

MAINTENANCE

System operating time for the batteries can be

determined by dividing the battery capacity

(amp-hours)

by

the

average system current

drain.

The

CR10 draws <1 mA

in

the quiescent

state,

13

mA

while

processing, and

46

mA

during an

analog measuremen! the

length

of

operating time

for

each datalogger instruction

is

listed

in

the programming

section.

Typical

current

requirements for

common CR'|0

peripherals are given

in

Table

14.2-1.

14.3

CAMPBELL SCIENTIFIC

POWER

SUPPLIES

The

PS12 Power Supply

is

available from

Campbell Scientific with either alkaline

or

lead

acid batteries,

the

PSl2ALK

and PS12LA,

respectively. The

PS512M

is

also

a

lead acid

supply with two 9-pin null modem ports

for

communication

modems,

see Section

14.3.3.

The

PSl2ALK

has

8

D

cellalkaline

batteries,

the

PS12LA has

a

rechargeable lead acid

battery.

The

alkaline

batteries are discarded

after

use.

The

lead acid batteries should be

float charged

with

either AC power or a solar

panel.

The

lead acid battery supplies power

during

a

power

failure

or

in

times

of

low

charge

with

a

solar panel.

The CH12R and CH512R contain the same

circuitry as

the

PS12LA and

PS5'12M,

respectively.

They

are

used to float charge an

external

12

VDC

Yuasa

battery using AC

or

solar

power.

No internal batteries are contained

in

the CH12R and

CH512R. Their

operation,

however, is identical to that

of

the

PS12LA and

PS512M.

Other power supply options are

connecting

a

12

volt battery directly to the

CR10, Section 14.5, or supplying power

from

a

vehicle,

Section

14.6.

The

PS12 Power Supply provides

12

volts,

regulates incoming AC

or

DC power, limits

current from

the

battery, and provides circuitry

to connect an

external

12

volt battery.

The

terminals on

the

PS12 are exposed by

unscrewing the two set screws, as shown

in

Figure 4.3-1.

The

two

12

volt and

two

ground terminals are

for supplying power to the datalogger, or

other

12

volt devices.

The two

terminals,

labeled CHG, are

for

connecting a 20 VDC adapter or solar panel to

charge

lead acid batteries.

The

charge input

can

be either AC

or

DC, and

it

does

not matter which

terminal

is positive or

14-2

negative.

The

voltage

input must be

within

16

to 26 VDC,

or

16

to 26

VAC

RMS.

The ON-OFF switch controls power to

the

12

V

ports.

Charging

of

lead acid batteries still

occurs when

the

switch is

off.

The

red charge

light

is

on when

a

charging source

is

connected

to

the

power supply.

The

connectors labeled

INT

and

EXT are

for

connecting

the

internal (power supply) battery

and an external battery,

respectively.

A five foot

cable, with connector, is included with

the

supply for connection to an external battery.

This

is

commonly

used for supplying power to

the datalogger while changing power supply

batteries.

A

thermal

fuse

in

the

power

circuit

limits source

current.

lf excessive

current

is

drawn, the fuse

gets hot, increases in resistance,

and

limits

current.

When

the

problem

is

fixed, the

fuse

cools and

the

resistance decreases, eventually

allowing current

to

pass.

When excessive

current

is

drawn due

to

shorting

the

power

to the

Wiring

Panel,

allow

10

to

15

seconds

for

the fuse to cool before connecting power.

14.3.1

PS12ALK

ALKALINE

POWER SUPPLY

The

PSl2ALK

utilizes

I

alkaline

D

cells

mounted in place

of

the

lead acid battery shown

in

Figure 14.3-1. The

PSl2ALK

can also

be

used with

a

lead acid battery connected to the

external battery port,

in

this case the alkaline

batteries act as

a

backup.

Before installing

the

alkaline batteries,

connect

all necessary sensor leads, control lines, and

power

leads.

The CR10

can

be

turned on and

off with the switch

on

the

PS12ALK.

To

replace

the

batteries

without

losing the

datalogger program and

data:

1)

do

not turn the

power switch off,

2)

connect an external battery

to

the

port labeled EXT with the supplied

6

foot

cable,

3)

remove the old batteries,

4)

replace

with

new alkaline

D

cell batteries, and

5)

remove

the

external battery.

A fresh set of eight alkaline

D

cells has

12.4

volts and

a

nominal rating of 7.5 amp-hours at

20'C.

The amp-hour

rating decreases with

temperature as shown

in

Table 14.3-1.

Datalogger

lnstruction

10

can be used to

monitor battery

voltage.

Replace the alkaline

cells

before

the

CR10 battery voltage drops

below 9.6

V.

Campbell Scientific CR10 CR10 Measurement and Control - Page 194

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