Honeywell Pressuretrol P7810C Quick Start Manual page 6

P7810C,D PRESSURETROL
1
+mA
1/4 IN. NPT
(MODULATE)
STEAM
PRESSURE
CONTROL
SENSOR
1/4 IN. NPT
STEAM
PRESSURE
HIGH LIMIT
CONTROL
SENSOR
1/2 IN. NPT
1 USE COPPER CONDUCTORS ONLY
Fig. 6. P7810C,D Pressuretrol® Controller.
P7810 Pressuretrol ®
For P7810C,D Pressuretrol® Controllers with more than one
function (control and modulate), adjust setpoints and
differentials separately for each function.
CAUTION
Equipment Damage Hazard.
Improper settings of control setpoint and control
range dial arrows can damage the P7810.
Do not set control setpoint or control range dial arrows
past the scale plate endpoints.
Adjust setpoints and differentials using the dials on the front
of the P7810C,D Pressuretrol® Controller.
Set the dials to the desired point by aligning the center of the
dial arrow with the desired mark on the scale plate. See Fig. 7.
Fig. 7. Setting control setpoint and control range dials.
P7810C,D On/Off Control (Fig. 8)
When pressure increases to the control setpoint, the P7810
Pressuretrol® Controller relay contacts (2K1) open. The relay
contacts close when the pressure decreases to a level at or
below the control range setting differential. This cycle
continues until power is removed, opening the relay. The
differential is a subtracted value from the setpoint adjustment.
65-0235—1
®
CONTROLLER
LINE VOLTAGE
COM L2
GND
-mA
N.O. 1 L1
M11895A
Controller (Fig. 6)
SCALE
PLATE
DIAL ARROW
M4880A
The upper operating point is determined by the control
setpoint, while the lower operating point is determined by the
control range setting (control setpoint minus the differential
setting). See Fig. 8.
ON
CONTROL
RELAY
(K)
OFF
CONTROL
RANGE
Fig. 8. P7810 control function versus pressure.
Modulate Control (P7810C Only)
The P7810C adds 4 to 20 mA modulation output and uses
two additional dials. The pressure sensor output is fed to an
error and gain amplifier to perform the modulation determined
by the control dials.
The dials mounted on the P7810C face adjust the current
output for a given set of pressures. When the pressure
decreases to or below the modulation setpoint, the current is
20 mA. The current remains constant at all pressures below
the modulation setpoint.
The modulation range is an additive value to the modulation
setpoint value.
When the pressure increases above the modulation setpoint,
the current decreases linearly until the modulation range point
is reached. The output current is 4 mA at and above this
pressure. See Fig. 9.
20 mA
MODULATION
CURRENT
4 mA
MODULATION
SETPOINT
Fig. 9. P7810C modulation current versus pressure.
On-Off Safety Limit (P7810C,D)
When pressure increases to the limit setpoint, the (1K1)
contacts open and the P7810C,D indicates a safety lockout
by flashing the yellow and green LED. The P7810C,D remains
in this condition until the manual reset button (see Fig. 1) is
pressed.
6
DIFFERENTIAL SETTING
CONTROL
SETPOINT
PRESSURE
M4881B
MODULATION
RANGE
PRESSURE
M4882