PD2-6262 Helios Large Display Analog Dual-Input Rate/Totalizer Instruction Manual
43
Acknowledging Relays
There are two ways to acknowledge relays programmed for manual reset:
1. Via the programmable front panel function keys F1-F3 (Default: F3 assigned to ACK).
2. Remotely via a normally open pushbutton wired across one of the digital inputs and the +5 V
terminals on the digital I/O terminal, or using the F4 digital input, which is triggered with a contact
closure to COM, or with an active low signal (see page 18).
When the ACK button or the assigned digital input is closed, all relays programmed for manual reset are
acknowledged.
Figure 23. Acknowledge Relays w/Function Key or Digital Input
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
overheating 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.
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 operating 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 to10.000, 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.
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
MENU
RESET
F1
MAX
F2
ENTER
F3
