Troubleshooting Tips
Rapid Cycle
Explanation
Irrigation Craft pioneered this feature in 1989. Rapid Cycle on Irrigation Craft pump stations is refined to avoid nuisance alarms. Other manufacturers have at times offered this feature but their programming may have been insufficient to prevent nuisance alarm problems.
The purpose of the RAPID CYCLE feature (also called SHORT CYCLE), is to prevent pump motor and motor starter damage caused by excessively frequent starts, and also to prevent a pressure cycling of the mainline that might occur if the pumps are starting and stopping rapidly. Excessive starts can be caused by problems at the pump station, or problems in the field.
The feature works by keeping track of how often the main pumps are starting and stopping over time. If there is a jockey pump on the pump station the RAPID CYCLE feature does not apply to the jockey pump. Irrigation Craft pump stations will not be “fooled” by normal maintenance operations being performed on the irrigation system.
Pump Station Causes of Rapid Cycle
1. Is the flow switch working properly? Irrigation Craft flow switches can be used to keep a pump running down to 1 gpm or less when required. Other brands of pump stations often cannot keep a main pump running below about 25 gpm, jockey pumps often cannot be kept running below about 15 gpm (other manufacturer’s flow switches may not be sensitive enough to reliably detect flow rates lower than the figures given). Please note that on systems with very low flow rates either a jockey pump should be used or main pumps should be used, and also pumps should be used that are less vulnerable to recirculation which occurs at low flow rates.
2. Pressure tank air pre-charge may be incorrect, pressure tank air bladder may have failed, if non-captive air type tank then the air level maintenance valve may be malfunctioning.
3. Are both the jockey and main start pressure switches correctly adjusted, and are the switches opening and closing their contacts correctly? If a jockey pump is in the system, is the jockey pump able to start and prevent the main pumps from starting under low flow conditions?
4. Was the correct jockey pump installed? Incorrect jockey pumps are a frequent problem in the industry. The jockey pump must be selected properly to keep the main pumps off until flow rates are high enough to justify a main pump turning on, and the controls must then maintain that main pump in operation correctly.
5. With the smallest zone or flow rate requiring a main pump start turned on, does a main pump continue to operate at all times, or does the main pump turn off and have to start again? If the main pumps turn on and off repeatedly a flow switch may be the problem, or a pressure switch adjustment may be the cause.
6. Is there a leak in any of the pump intake lines?
7. Are there any loose wires anywhere in the control panel or at the sensor connections? A loose wire may cause intermittent pump starts and stops.
8. Have maintenance operations at the pump station caused repeated main pump starts and stops? On Irrigation Craft stations Avoid this problem by depressing the reset button before leaving the station. Depressing the reset button will reset all counters and timers.
Field Problems Causing Rapid Cycle
1. Small leaks in the mainline, or leaking valves. The pump station is designed to feed the smallest leaks with the jockey pump, which is not protected by “rapid cycle”. However, if a leak grows larger than the jockey pump can supply, a main pump may be started. Once the main pump starts, the main pump may be able to feed the leak and also shut down, in which case the station will fail on rapid cycle. If this is the cause then the station should be adjusted to prevent this.
2. Have maintenance operations in the field caused repeated main pump starts and stops? Avoid this problem by keeping water flowing at all times when performing maintenance operations. Avoid turning single zones on and off repeatedly. This scenario is a unlikely on Irrigation Craft pump stations because of refined programming.
