Large Display Temperature Meters
Instruction Manual
40
OPERATION
Overview
The Large Display Temperature Meter accepts the J, K, T, E, R, and S
thermocouples and 100
Ω
platinum RTDs as inputs. The meter will display the
temperature in either Fahrenheit or Celsius scales on a 4½ digit display. Options
include up to four relays for external switching at alarm points as well as an
isolated 4-20 mA transmitter output.
The front panel consists of six seven-segment LEDs as well as eight
programming/operational LEDs. The programming/operational LEDs provide the
following indication:
LED During
Programming During
Operation
1
Alarm 1
Alarm 1
2
Alarm 2
Alarm 2
3
Alarm 3
Alarm 3
4
Alarm 4
Alarm 4
S
Set point indicator
None
R
Reset point indicator
None
4
4 mA output indicator
None
20
20 mA output indicator
None
Refer to Figure 37 on page 65 for PD755.
Refer to Figure 38 on page 65 for PD756.
Refer to Figure 39 on page 65 for PD757.
The four alarm status LEDs indicate alarm condition only and do not represent
relay status when set points are set up for non-latching relay mode. For instance,
if alarm 1 is programmed for a high alarm at 500 with manual reset of the relays.
If the operator resets the relays when the display reads 650, LED #1 will stay on
until the display falls below 500.
Set points set up for latching relay mode will reflect the status of the LEDs,
regardless of the status of the alarm condition. For instance, when a latching
relay is acknowledged the corresponding status LED will extinguish.
Another example:
•
With manual reset of the relays enabled.
•
Alarm 1 set up as non-latching and programmed for high alarm.
Set at 100
Reset at 50
•
If the operator resets the relays when the display reads 80.
•
LED 1 will stay on until the display falls below 50.
