Sierra Instruction Manual ATEX Certified Units: 640S-EEX & 780S-EEX
Page 8 of 15
5. Remote Electronics
Sierra Thermal flow transmitters with E3 in the model code have remote electronics. They have
a cable with Ex glands between the sensor and the electronics. With these models it is not
possible or allowed to disconnect the cable from the sensor side. It is possible to disconnect the
cable and re-
mount it using the electronics’ side.
Please observe the following: Ensure that the power to meter has been disconnected before you
open the EEx d housing. Then open the terminal housing (short dome on the housing) This
dome is sealed with a set-screw in the edge of the dome. Unscrew the set-screw and screw the
dome from the housing. Record the color of the wires to terminals 16 thru 20. Disconnect the
sensor wires (See diagram below).
Fig 2 Wiring diagram remote probe (E3 option)
Unscrew the cable gland and remove the wire from the electronics housing.
To re-install the cable, insert the cable in the cable gland. Then connect the wires to terminals
16
– 20, ensuring that they are connected identically to what they were before you removed the
cable.
Assemble the cable gland according
to the cable gland manufacturers’ instructions (See
enclosed), close the housing, tighten the set-screw, and power the system up.
NOTE: The unit has some built in electronic wire length compensation. It is possible to shorten
the cable or to extend it up to +- 25% of the cable length. Use only Sierra cable PN 23-0221.