|AMERICAN AUTOMATED TIMER CONTROLS
Repeat Cycle Timer Controller
TIMER CONTROL OPTIONS
Repeat Cycle Timers provide for an “off” periods followed by an “on” or “run time” period when water is available to pump. Assures no excess water will be delivered downstream (Excess Water Use Alarm).
Time of day controls provide for controlling pumping to the downstream at specified time of day such as spray irrigating at night.
PLC (Programmable Logic Controller) Controls provide for more economical inclusion of counters and ETM's (Elapsed Time Meters) and data logging for enhanced operator utility. The PLC based controllers can provide for a peaking operation instead of an override. By peak flow operation the excess water use alarming can still be provided thus not turning the controller into demand based operation.
TIMER CONTROL OPERATION
Programmable Logic Controller
The pump control panel is equipped with float switches to control the timed doses to be discharged. The water level must be high enough to overcome the "Redundant Off" (Bottom) float in order for the pump to be permitted to run. This float is redundant to the timers. That is to say in the event the timer does not turn off the pump the Redundant off float will protect the pump from running out of water and shut the pump off.
When the water level rises high enough to overcome the "Dose Enable" (second) float and the timer is in a pump enable mode, the pump will activate. The pump shall continue to run for the length of time as set on the pump run timer, and will then shut off. The pump shall remain off until the time clock enters a new pump enable mode, at which time the pump will activate (as long as the "Dose Enable" float is still up) and will run until the pump run timer finishes timing out. This process shall continue until the water level drops below the "Dose Enable" float and the pump run timer has timed out.
The operation of the redundant off float and the dose enable float may be combined into one operation, however the designer must recognize that frequent short cycling the dose volume is the result of this operation and it must not have a negative effect on any downstream process.
DUPLEX SPECIFICATION GUIDANCE
Duplex timer control specifications must include a pump fail alarm separate from the high level alarm. In the event one pump becomes inoperable, the system will immediately go to discharging and a rate of one half of the design daily flow. If the demand is less than half of the design flow the water will not rise in the pump chamber to allow for an alarm. A current senor or flow sensor must be integrated into the circuit to alarm a pump fail condition.
OVERRIDE VS. PEAKING OPERATION GUIDANCE
The control system may be equipped with a timer override circuit to manage peak flows and excess water use. If the water level continues to rise enough to overcome the "Timer Override" (third) float and any override selector switch is on, the pump will be activated, regardless of the time clock position. The pump will continue to run until deactivated by the override circuit, at which time the pump will shut off and the normal pumping cycle shall resume. This operation turns the controller into a demand dose system as opposed to a timer based system.
A peak flow controller may be equipped with a peak enable circuit to manage peak flows and excess water use up to a specified peak flow capacity. If the water level continues to rise enough to overcome the "Peak Enable" (third) float and any override selector switch is on, the pump will be activated, regardless of the rest time position and start a pump cycle. The pump will run for the period of time as set by the run timer and then deactivate. A shortened rest time period will follow to provide for enhanced time dosing. When the water level drops below the peak enable level, the normal pumping cycle shall resume. This operation turns the controller into an enhanced time dose system as opposed to demand based system.
HIGH LEVEL ALARM
If the water level continues to rise enough to overcome the "High Level" (fourth) float, the audio/visual alarm shall activate until silenced by pressing the Test-Normal-Silence switch to the silence position. The alarm circuit shall automatically reset when the "High Level" float returns to its normal position. Note the high level alarm float should be placed high enough in the pump tank to provide flow equalization to minimize nuisance alarms.
|RECOMMENDED TIMER CONTROL MODELS
||Simplex Timer Control w/ PLC (Counter & ETM in PLC)
||Simplex Timer Control w/ PLC & 24-hr Clock (Counter & ETM in PLC)
||Simplex Timer Control w/ Repeat Cycle Timer
||Simplex Timer Control w/ Repeat Cycle Timer, Cycle Counter & ETM
||Duplex Timer Control w/ PLC (Counters & ETMs in PLC)
||Duplex Timer Control w/ PLC & 24-hr Clock (Counters & ETMs in PLC)
||Combo Simplex Timer Control w/ PLC (Counter & ETM in PLC)
||Combo Simplex Timer Control w/ Repeat Cycle Timer, Counter & ETM
Onsite Waste Water Control Design