To control water levels in sumps, dams, tanks, etc. Operation is the same as the normal DCU but this unit can control 2 pumps operating at different levels.
3 Float switch (24V DC) – 4 Wire control: Stop float – normally closed contact connected to terminals 6 + 7. First start float – normally open connected to terminals 5 + 6. Second start float – normally open connected to terminals 4 + 6.
Closing 5 + 6 (1st start float) will energise relay No. 1 and closing 4 + 6 (2nd start float) will energise relay No.2. Both start relays will remain energised until the stop float opens between terminals 6 + 7. This system is used for “Duty Pump” and “Stand-by Pump” applications.
Where only one pump with an alarm is required, relay No.1 is used for the pump and relay No. 2 for the alarm. Where 2 pumps and alarm are required, a normal DCU can be used for the alarm operation. If this system is used, a seperate float must be used dedicated to this DCU. The interconnection of the two 24 Volt float outputs of the DCU/2 and DCU must be avoided at all times.