PD8-6060 Explosion-Proof Dual Analog Input Process Meter
Instruction Manual
48
Acknowledging Relays
There are three ways to acknowledge relays
programmed for manual reset:
1. Via the programmable front panel function keys
F1-F3 (Example: F3 assigned to ACK).
2. Remotely via a normally open push button wired
to the F4 terminal.
3. Remotely via a normally open push button wired
to one of the digital inputs and the +5 V terminal
on the digital I/O connections.
When the ACK button or the assigned digital input is
closed, all relays programmed for manual reset are
acknowledged.
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
30.000
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 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
4 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.
+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
