Dwyer TTE - Manual (Page 3)

Setting and Calibrating the User Settable Range
By setting SWITCH 2, 3, and 4 on, the RTD Transmitter may
be adjusted to a custom user specified range. The range
may be any values between –30°F and +250°F (-34 to
+121°C) with a MINIMUM SPAN of 40°F (22°C).
Equipment Required
In order to calibrate the unit for a custom range, a precision
RTD simulator that can simulate a 1000 OHM DIN type RTD
or precision decade box is required. The device must be
capable of generating the correct RTD resistance to 0.1% or
better.
Calibration Procedure
1. Set DIP SWITCHES 2, 3 and 4 ON.
2. Remove the RTD sensor leads from terminals 5 and 6
(Fig. B). Connect the precision RTD simulator or
decade box to terminals 5 and 6.
3. Wire instrument as previously discussed. A current
meter may be wired in series with the unit to verify the
correct current output, but this is not necessary for
calibration. Apply power to the unit.
4. If a precision RTD simulator is used, make sure it is set
to simulate a 1000 OHM DIN 0.00385 RTD. Then set it
to the desired minimum temperature. If a decade box is
used refer to the table in Appendix A (°F) or Appendix B
(°C) and set it to the resistance that represents the
desired minimum temperature.
5. Press the ZERO button. If the unit has the optional LCD,
the display will read ZERO OK momentarily. If a current
meter is wired, it will read 4.00mA.
6. Repeat step 4 using the value for the maximum desired
temperature.
7. Press the SPAN button. If the unit has the optional LCD,
the display will read SPAN OK momentarily. If a current
meter is wired, it will read 20.00mA.
8. Turn off power to the unit. Disconnect the RTD simulator
or decade box and reconnect the RTD sensor to
terminals 5 and 6. Calibration is complete.
Note: The calibration procedure does not effect the
calibration of any of the built in ranges.
°F and °C Selection
If the unit has the optional LCD display, DIP SWITCH 1 sets
the display to read in °F or °C. SWITCH 1 “OFF” = °F
SWITCH 1 “ON” = °C.
Output Current Display
If the unit has the optional LCD display, the lower display will
show the output current if DIP SWITCH 5 is “ON”. Setting
DIP SWITCH 5 “OFF” causes the lower display to be blank.
Open RTD Protection
Upon detecting an open RTD, the unit may be set to force
the output to read 3.5mA or 21mA based upon the setting
of DIP SWITCH 6.
SWITCH 6 “OFF”, output forced to 3.5mA
SWITCH 6 “ON”, output forced to 21mA
Calibration
The unit requires no calibration. An internal precision resistor
continually self calibrates the unit. Calibration may be
verified by removing the sensor leads and testing the unit
against a precision RTD simulator or a precision decade
box. If the unit is found to out of calibration it must be
returned to the factory for service.
MAINTENANCE
Upon final installation of the Series TTE Explosion Proof RTD
Temperature Transmitter, no routine maintenance is
required. A periodic check of the system calibration is
recommended. The Series TTE is not field serviceable and
should be returned if repair is needed (field repair should not
be attempted and may void warranty). Be sure to include a
brief description of the problem plus any relevant application
notes. Contact customer service to receive a return goods
authorization number for shipping.
E-90-TTE:Model PHO-1 12/22/08 2:04 PM Page 3