Why use a "Redundant/Backup" Controller?
A Redundant/Backup controller is analogous to a spare tire. One hopes that they never have a flat tire. However, flats happen; sometimes at the most inopportune time.
Why consider a backup controller?
1) The primary controller is inoperative/off-line. Possible case: Lightning, electrical surge, tripped- breaker, maintenance, etc.
2) The primary system's level sensor is inoperative
Configuring a redundant system:
1) Some primary controllers provide dual-sensor inputs (two analog sensors or an analog sensor [primary] and floats [backup]). That may be adequate if one only expects a sensor failure. However, a complete/separate redundant/backup controller provides significant additional advantages (i.e. piece of mind)
2) Redundancy may include:
a) Placing the redundant controller on the alternate side of the lighting panel/control transformer
b) Powering the redundant control with an Uninterrupted Power Supply
Contegra's Redundant Controllers:
Duplex Pumping stations - Refer to the CD 2R
Triplex Pumping Stations - Refer to the CD 3R