Delta OHM DO 9761T Bedienungsanleitung Seite 7

Programming the parameters
It is possible to select the corresponding quantities:
- Dry bulb temperature (TD °C)
- Wet bulb temperature (TW °C)
- Dew point temperature (DP °C)
- Relative humidity (% RH)
- Absolute humidity (a gr/m 3 )
- Mixing ratio (x gr/kg).
The range that may be set for each quantity is:
- Dry bulb, wet bulb and dew point temperature: -50.0...+199.9°C
- Relative humidity: 0.0...100.0% RH
- Absolute humidity: 0.0...1999 gr/m
- Mixing ratio: 0.0...1999 gr/kg.
Parameters for the DO 9761T
P1 Physical quantity on which depends the operation of the relays and
the analog output (TD, TW, DP, % RH, gr/m
P2 Value corresponding to 4 mA at output.
P3 Value corresponding to 20 mA at output.
P4 Delay time in intervention of relay A. May be set between 0 and
225 seconds both during the opening and the closing.
P5 Delay time in intervention of relay B. May be set between 0 and
225 seconds both during the opening and the closing.
P6 Display and setting of the capacitive value at 75% RH and of the
slope value of the humidity sensor.
P7 Calibration of Pt100 probe, output current calibration at 4 mA and
20 mA.
Parameters for the DO 9861T
P1 Physical quantity on which depends the operation of the analog out-
put 1 (TD, TW, DP, % RH, gr/m
P2 Physical quantity on which depends the operation of the analog out-
put 2 (TD, TW, DP, % RH, gr/m
P3 Value corresponding to 4 mA at analog output 1.
P4 Value corresponding to 20 mA at analog output 1.
P5 Value corresponding to 4 mA at analog output 2.
P6 Value corresponding to 20 mA at analog output 2.
P7 Physical quantity on which depends the operation of relay A (TD,
TW, DP, % RH, gr/m 3 , gr/kg).
P8 Physical quantity on which depends the operation of relay B (TD,
TW, DP, % RH, gr/m 3 , gr/kg).
P9 Delay time in intervention of relay A. May be set between 0 and
255 seconds both during the opening and the closing.
P10 Delay time in intervention of relay B. May be set between 0 and
255 seconds both during the opening and the closing.
P11 Calibration of Pt100 probe, display and setting of the capacitive
value at 75% RH and of the slope value of the humidity sensor.
P12 Current calibration of output 1 at 4 mA and 20 mA.
P13 Current calibration of output 2 at 4 mA and 20 mA.
To alter one of the parameters, press the PRG key until the message
corresponding to the parameter that is to be changed appears on the
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display. Using the and keys, bring the parameter shown to the desi-
red value. Press OK to confirm.
Before starting programming, select the quantity to be displayed with the
TD/TW and UNIT keys; the instrument will use this as the default value. If
there is an interruption in the power supply this value will be displayed
when it starts again.
To change the quantity shown, just press UNIT or TD/TW.
Setting the relay SET points
- Press the SET key, the ON symbol appears on the display and the let-
ter A to indicate that the value displayed corresponds to the switching-
on threshold of relay A.
- To change this value press the
- Press SET, the OFF symbol appears and the letter A to indicate that the
value displayed corresponds to the switching-off threshold of relay A.
- To change this value press the
- Press the SET key, the ON symbol appears on the display and the let-
ter B to indicate that the value displayed corresponds to the switching-
on threshold of relay B.
- To change this value press the
- Press SET, the OFF symbol appears and the letter B to indicate that the
value displayed corresponds to the switching-off threshold of relay B.
- To change this value press the
- Press SET, the instrument stores the values and returns to normal ope-
ration.
NOTE: While the SET point is being set (ON or OFF symbols lit), the
instrument returns to normal operation if no key is pressed for
2 minutes.
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Calibration of the humidity sensor in DO 9761T and
DO 9861T transmitters
Calibrating the offset of the humidity sensor:
- Insert the probe in the container of the 75.4% relative humidity satura-
ted solution. Wait at least 30 minutes.
- With the UNIT key select the indication of relative humidity (% RH) on
the display.
- With the TD/TW key select the indication of the dry bulb temperature
(TD).
- Press the CAL and UNIT keys together; the message CAL will appear
at the top of the display.
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- With the and keys adjust the relative humidity value indicated on
the display to the correct value corresponding to the temperature and
saturated humidity of the salt used.
- Wait a few minutes to ensure that the reading is stable.
- Press CAL to confirm this value. The message CAL will disappear.
- Remove the probe from the container and replace the cap of the contai-
ner immediately.
Calibrating the slope of the humidity sensor:
- Insert the probe in the container of the 33% relative humidity saturated
solution. Wait at least 30 minutes.
- With the UNIT key select the indication of relative humidity (% RH) on
the display.
- With the TD/TW key select the indication of the dry bulb temperature
(TD).
- Press the CAL and UNIT keys together; the message CAL will appear
at the top of the display.
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- With the and keys adjust the relative humidity value indicated on
the display to the correct value corresponding to the temperature and
saturated humidity of the salt used.
- Wait a few minutes to ensure that the reading is stable.
- Press CAL to confirm this value. The message CAL will disappear.
- Remove the probe from the container and replace the cap of the contai-
ner immediately.
NOTE: The point at 75% RH must always be calibrated before the one at
33% RH.
N.B.: If the instrument measures a value higher than 50% RH it calibrates
the offset, if it measures a lower value it calibrates the slope of the
sensor.
Setting the capacitive values of the relative humidity
sensor
If the capacity values of the relative humidity sensor are known, it is pos-
sible to set these values without any need to perform calibration with
salts, as described in the previous paragraph.
- Press the PRG key until the message P6 (P11 for the DO 9861T)
appears on the display.
- The capacity value of the sensor in pF corresponding to 75% relative
humidity appears at the bottom of the display.
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- With the and keys adjust the capacity value of the sensor corre-
sponding to 75%.
- Press the CAL key.
- The value corresponding to the gain of the relative humidity sensor
appears at the bottom of the display, expressed in pF/% RH @ 75%.
- The gain value of the sensor may be adjusted with the
this value is supplied.
- Press OK to confirm.
Calibrating the Pt100 temperature sensor (100 Ω at 0°C)
- Connect the probe to the instrument. Press the PRG key until the mes-
sage P7 (P11 for the DO 9861T) appears on the display.
- Press the CAL key once (two times for the DO 9861T). The message
P7 or P11 appears at the bottom of the display while the temperature is
shown at the top.
- Immerse only the Pt100 sensor and a precision thermometer, for refe-
rence, in the zero calibration bath (water distilled). Wait until the reading
has become stable.
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- With the and keys adjust the temperature value measured by the
Pt100 sensor so that it coincides with the value on the reference ther-
mometer.
- Immerse the Pt100 sensor and the reference thermometer in the full
scale calibration bath. Wait until the reading has become stable.
- With the and keys adjust the temperature value measured by the Pt100
sensor so that it coincides with the value on the reference thermometer.
- Press OK to confirm.
N.B.: If the temperature shown by the instrument is between ±12°C, the
instrument calibrates the probe offset, otherwise it calibrates the
gain.
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