PD6600 Series Loop-Powered Process Meters
Instruction Manual
6
Multiple Outputs
•
Two open collector outputs (standard)
•
Two solid state relays (optional)
•
One 4-20 mA output (optional)
The open collector outputs and relays generally
operate in the same manner, with the major exception
being the open collectors are not available for pump
alternation and the relays are not available with pulse
features. The open collectors and relays can be
controlled either automatically or manually.
The isolated analog output signal can be configured
to represent the process variable (PV1, PV2, or
retransmit). It can also be reverse scaled such that
the meter’s high calibration value outputs 4 mA and
the meter’s low calibration outputs 20 mA.
Pump Alternation
(
ALTERN
)
For pump control applications where two similar
pumps are used to control the level of a tank or a well,
it may be desirable to have the pumps operate alter-
nately. This prevents excessive wear and overheating
of one pump over the lack of use of the other pump.
Pump alternation uses both relays in tandem to alter-
nate between two similar pumps. The
ALTERN
menu
is only available under Output 1 and will automatically
set Output 2 to pump alternation as well.
Pump Alternation Example
The following is an example application where the re-
lays are programmed for pump alternation.
On & Off Point Programming
Relay
On Point
Off Point
Function
1
7000
1000
Controls backup pump
2
6000
1000
Controls main pump
The following graphics provide a visual representation
of a typical pump alternation application:
Note: Open Collectors can be used for high and low
alarm indication.
6245
GAL
!
6245
GAL
!
7153
GAL
!
995
GAL
Relay #2 turns the main pump on at 6000 gallons and turns it o
ff at
1000 gallons.
With the PumpAlternation feature activated, the next time the level
reaches 6000 gallons, relay #1 transfers and starts the backup
pump.
If the backup pump is not able to keep up, and the level reaches
7000 gallons, relay #2 transf ers and starts the main pump as well.
Once the level has dropped below the reset points, both relays will
turn off .
