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VI. ALARM & OUTPUT FEATURES
1.
4-20 mA Output
– Two 4-20mA outputs are provided at terminals AO1/V- and AO2/V-. These signals
are proportional to the chemical feed rate.
2.
RS-485 Modbus Communication
– This feature allows the HC-220 to be monitored and controlled by
a computer. See Hydro Instruments’ Modbus Communication Setup document for further details.
3.
Alarm Relay Output
– Power ratings: 10A @ 277VAC, 12A @ 125VAC or 5A @ 250VAC.
4.
Acknowledgement
– Press the “minus”
key to acknowledge the alarm.
NOTE: Any of the below contacts will activate this alarm relay. The alarm is non latching.
Control Mode
Alarm Condition
Description
Action
Flow Pacing
Flow Signal Loss
PV1 Signal below 3 mA
Valve Close or Hold Position**
Flow Pacing
Low Flow
PV1 Signal below set point*
None
Residual/ORP
Res/ORP Signal Loss
PV2 Signal below 3 mA
Valve Close or Hold Position**
Residual/ORP
Low Set Point
PV2 Signal below set point*** None
Residual/ORP
High Set Point
PV2 Signal above set point*** None
Compound Loop Flow Signal Loss
PV1 Signal below 3 mA
Switch to Residual/ORP Condn 1
Compound Loop Low Flow
PV1 Signal below set point*
None
Compound Loop Res/ORP Signal Loss
PV2 Signal below 3 mA
Switch to Flow Pacing Control
Compound Loop Low Set Point
PV2 Signal below set point*** None
Compound Loop High Set Point
PV2 Signal above set point*** None
* See Section III.1.i. – User defi ned fl ow signal level below which alarm is activated.
** See Section III.1.b. and III.2.b. – User selects this parameter in Confi guration Mode.
*** See Section III.2.i. & III.2.j. – User selects an acceptable range for Residual/ORP/pH.
3e. In Manual Mode the feed rate will be displayed and can be adjusted with
and
keys.
DISPLAY (PO1)
Chemical Feed Rate
(%, PPD, …)
3f. Alarm messages are displayed.
DISPLAY
ALARMS
(none, Flow Signal Loss, …)
