Precision Digital PD6000 - Manual (Page 59)

Model PD6000 Analog Input Process Meter Instruction Manual
59
Pump Alternation Control Applications (Altern)
For pump control applications where two or more similar pumps are
used to control the level of a tank or a well, it is desirable to have all the
pumps operate alternately. This prevents excessive wear and overheat-
ing of one pump over the lack of use of the other pumps.
Up to 8 relays can be set up to alternate every time an on/off pump
cycle is completed. The set points and reset points can be programmed,
so that the first pump on is the first pump off.
Application #1: Pump Alternation Using Relays 1 & 2
1. Relays 1 and 2 are set up for pump alternation.
2. Relays 3 and 4 are set up for low and high alarm indication.
Set and Reset Point Programming
Relay Set Point Reset Point Function
1 30.000 10.000 Controls pump #1
2 35.000 5.000 Controls pump #2
3 4.000 9.000 Controls low alarm
4 40.000 29.000 Controls high alarm
Pump Alternation Operation
1. Pump #1 turns on when level reaches 30.000, when level drops
below 10.000 pump #1 turns off.
2. The next time level reaches 30.000, pump #2 turns on, when level
drops below 10.000 pump #2 turns off.
3. If the level doesn’t reach 35.000 pump #1 and pump #2 will be op-
erating alternately.
4. If pump #1 cannot keep the level below 35.000 pump #2 will turn on
at 35.000, then as the level drops to 10.000 pump #1 turns off,
pump #2 is still running and shuts off below 5.000.
5. Notice that with the set and reset points of pump #2 outside the
range of pump #1, the first pump on is the first pump to go off. This
is true for up to 8 alternating pumps, if setup accordingly.
6. Relay #3 will go into alarm if the level drops below 4.000 and relay
#4 will go into alarm if the level exceeds 40.000.
7. Adding the 4 external relays expansion module allows using the 4
SPDT internal relays for pump alternation and the 4 SPST external
relays for high, high-high, low, and low-low alarm indication.