ProtEX-MAX PD8-6001 Explosion-Proof Feet & Inches Meter Instruction Manual
40
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 modules, or using the F4 digital input, which is triggered with a contact
closure to COM, or with an active low signal (see page 19).
When the ACK button or the assigned digital input is closed, all relays programmed for manual reset are
acknowledged.
Figure 19. 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 4 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
FT
0
IN
0
/
16
10
FT
0
IN
0
/
16
Controls pump #1
2
35
FT
0
IN
0
/
16
5
FT
0
IN
0
/
16
Controls pump #2
3
4
FT
0
IN
0
/
16
9
FT
0
IN
0
/
16
Controls low alarm
4
40
FT
0
IN
0
/
16
29
FT
0
IN
0
/
16
Controls high alarm
Pump Alternation Operation
1. Pump #1 turns on when level reaches 30
FT
, when level drops below 10
FT
, pump #1 turns off.
2. The next time level reaches 30
FT
, pump #2 turns on, when level drops below 10
FT
, pump #2 turns off.
3. If the level
doesn’t reach 35
FT
, pump #1 and pump #2 will be operating alternately.
4. If pump #1 cannot keep the level below 35
FT
, pump #2 will turn on at 35
FT
, then as the level drops to
10
FT
, pump #1 turns off, pump #2 is still running and shuts off below 5
FT
.
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 4 alternating pumps, if setup accordingly.
6. Relay #3 will go into alarm if the level drops below 4
FT
and relay #4 will go into alarm if the level
exceeds 40
FT
.
+5
I1
I2
I3
I4
O1
O2
O3
O4
G
DO 1-4
GND
ACK
PDA1044 Digital I/O Module
1
2
3
4
5
6
7
8
9
10
DI 1-4
