User Guide

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FRONT PANEL

Left panel

1. LCD display

2. Slope calibration trimmer

3. Coarse set point trimmer

4. Fine set point trimmer

5. Offset calibration trimmer

6. Selects actual measurement (MEASURE) or setpoint (SET) to

be displayed on the LCD

Right panel

7. Triple contact alarm to select the alarm in a normally-closed

(NC) or a normally open (NO) position. The alarm contact is

activated when the mV varies by more than ±200 mV from

the setpoint.

8. Control contacts:

– Three terminals marked "Control Select" to choose REDOX or

OXYDT for dosing reducing or oxidant chemicals

– Three terminals marked "Out mA Select" to select between

0 to 20 mA or 4 to 20 mA isolated output.

9. Output contacts:

– Two terminals marked "mA Output" for the isolated output

FUNCTIONAL DESCRIPTION WM 8920FUNCTIONAL DESCRIPTION WM 8920

FUNCTIONAL DESCRIPTION WM 8920

SINGLE SETPOINT ORP CONTROLLERSINGLE SETPOINT ORP CONTROLLER

SINGLE SETPOINT ORP CONTROLLER

Unplug the instrument from the power supply before

replacing the fuse.

BOTTOM CONNECTIONS

1. BNC socket for a combination ORP electrode

2. Input voltage supply socket

3. Output voltage socket (activated by a relay when the

measured reading is higher or lower than the setpoint

depending on the REDOX/OXYDT selection)

Specifications WM 8920D WM 8920U

RANGE -1000 to 1000 mV

RESOLUTION 1 mV

ACCURACY ±5 mV

(@20°C/68°F)

TYPICAL EMC ±6 mV

DEVIATION

mA OUTPUT User selectable 0 to 20 mA or 4 to 20 mA in

a -1000 to 1000 mV range with isolated output

CALIBRATION 2 point through trimmers

SETPOINT RANGE From -1000 to 1000 mV with 2 trimmers: "COARSE" and

"FINE" (activated through the "CONTROL SELECT" terminals:

"OXYDT" or "REDOX" for the oxidizing or reducing dosage)

ALARM CONTACT Normally open or normally closed isolated outputs

(Max. 2A, Max. 240V, resistive load, 1,000,000 strokes)

(activated when the ORP value varies by

more than ±200 mV from setpoint)

POWER SUPPLY 220/240V – 50/60Hz 110/115V – 50/60Hz

POWER SUPPLIES One plug for the oxidizing or reducing dosage (115 or 220V

FOR DOSING depending on the model, Max. 2A, 1,000,000 strokes)

ENVIRONMENT -10 to 50°C (14 to 122°F); max. 85% RH non-condensing

PROTECTION IP54

WEIGHT 1.6 Kg (3.5 lb.)

ENCLOSURE 181 x 221 x 142mm (7.1 x 8.7 x 5.6")

MATERIAL Housed in rugged, fiber-reinforced polypropylene case