Electro-Chemical Devices (ECD) HYDRA Ammonium - Manual (Page 23)

HYDRA NH
4
+ -N Page 15
The Outputs, mA 1 and mA 2, are held at the “Last Value” by Timer 2 during the Air Blast Cleaning Cycle.
The Outputs return to live readings one minute after the cleaning cycle ends. Timer 2 is a “one-shot”
timer triggered by Timer 1. When Timer 1 triggers, it starts Timer 2 which is set to run for a period of
time equal to the cleaning time plus one minute.
3.3.1 Manual Mode (4-20 mA Hold Function)
The % Output is displayed on the Home Screen for the NH4-N output, mA 1, and one screen above the
Home Screen for the pH % Output, mA 2.
The outputs can be set for manual control by simultaneously pressing both horizontal CALIBRATE keys
when the cursor is in front of the % Output line. An “M” will be displayed in front of the % Output value.
The Output will remain frozen at the last value until the Manual Mode is turned off. The Manual Mode
hold function is commonly used to freeze the outputs during maintenance and calibration cycles. While
in Manual Mode the Output can be adjusted between 0 and 99.9% using the CALIBRATE keys, very
useful for troubleshooting loop communication problems.
To exit Manual Mode press the left CALIBRATE arrow, ◄, three times and the “M” will disappear, the
Output will return to a live reading.
3.4 CONTACTS-ALARM RELAYS
3.4.1 Standard Configuration
Relay 1 is configured to control the Air Blast Spray Cleaner. It is triggered by Timer 1. Timer 1 is
configured as a periodic timer. The default setting for the period is 15 minutes with the duration set at
30 seconds. The period and duration of the cleaning cycle is user configurable and dependent on the
application. For water going to the clarifier an adequate cleaning cycle may be, every two hours for 15
seconds, where incoming water to an aeration basin may require a 30 second cleaning cycle every 15
minutes.
The Now clock is an arbitrary timer. The Period determines the amount of time that must pass before
the Now clock resets to 00 hours, 00 minutes and 00 seconds, 00: 00: 00. The On time is the start time
and it is set at 00: 00: 00, so every time the clock resets Relay 1 is triggered. The Off time sets the
duration of Timer 1 and is set at 00: 00: 30, thirty seconds. (See Section 3.2.6 above)
To Change how often the Spray Cleaner actuates, change the Per line to the desired period. The display
is set for days, hours: minutes: seconds, 0d00: 00: 00.
To Change the duration of the Cleaning cycle change the Off line. If the duration is changed from the
default value of 30 seconds then the Manual Mode Timer should be adjusted to allow the sensor to
stabilize after the cleaning cycle. Adjust Timer 2; Off line; to the new Clean Time (CT) + 1 minute.
Relay 2 is configured as a high alarm triggering at 10.0 ppm NH
4
+ -N. The value can be changed in the Set-
Up Menu as shown in Section 3.2.6. Changing the > sign to a < sign in the On line changes the set point
from a high to a low alarm. This can also be accomplished by setting the Off value higher than the On