Hanna-instruments HI 9910 Manual de usuario descargar pdf (Pagina 17)

ALARM

OFF

• The alarm ON/OFF switch is only to

disabledisable

disable

the alarm terminalthe alarm terminal

the alarm terminal (e.g. the buzzer will

not sound). However, all other functions such as

disactivation of the dosing relay remain unvaried, i.e. the pump

ceases to dose until the alarm condition is alleviated.

• The controllers provide for

automatic fail-safeautomatic fail-safe

automatic fail-safe security by

activating the alarm if there is a power failure, regardless of

whether the NC or NO configurations were chosen.

• The alarm is also activated if the maximum

dosage time is exceeded. The overdosage timer

can be set from 1 to 10 minutes. For HI 9911,

two timers for acid and alkaline corrections can

be independently selected.

• Once in an alarm condition, the alarm contact remains activated

until the switch is manually put in the off position or the

measurements returns to normal values.

Model Alarm is activated when the reading varies by :

HI 9910 0 to 2.0 pH (selectable) above or below the setpoint

HI 9911 0 to 2.0 pH (selectable) lower than the ALKALINE setpoint or

higher than the ACID setpoint

HI 9920 0 to 200 mV (selectable) above or below the setpoint

ALARM DOSING TIME

MINUTES

2.5

7.5

RECORDER OUTPUT CONNECTIONS

• The recorder output contacts are

isolatedisolated

isolated from the controller circuitry

to avoid interference. Select between

0 to 20 or 4 to 20 mA with the

selector (see 18 - Functional Diagram) before wiring. The output

mA value is proportional and is the pH or ORP value over the

entire range. For example, when measuring pH 7, the output

values are 10 mA or 12 mA based on whether the 0-20 or 4-20

output were respectively selected.

Output mA

selector

0/204/20

RECORDER

ALARM

MTC ATC

mA OUTPUT

TEMP. COMP.

4/20 0/20

HI 9910

SECONDS

090

MTC

°C

-10

2.0

0.5

1.5

COARSE

FINE SLOPEOFFSET

PROPORTIONAL SETTINGS

ALARM

OFF

SET

READ

ACID

DOSING

ALK

SET POINT

ALARM DOSING TIME

MINUTES

2.5

7.5

SET pH

ALARM

LINE

1 2 ... 12 13 14 15 16 17 18 19 20 21 22 ... 39 40

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Hanna-instruments HI 9910 Manual de usuario Pagina 17

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