Replacing RTDs on RDE300 series units

Occasionally it is necessary to replace RTD temperature sensors on RDE300 units. This may happen if the sensor is damaged or if the sensor is fixed with adhesive to a PV module that must be replaced or moved.

Beginning in 2021, RDE300 series units have connectorized RTD temperature sensors as shown in the photo below (white cables). Any replacement temperature sensors shipped will be the connectorized version.

If your RDE300 series unit has a connetorized RTD, replacement is simple. Unscrew the sensor at the mating connector and replace it with the new sensor provided by Atonometrics. Make sure that the seal is tight, to avoid water penetration.

NOTE: Older RDE300 series units shipped before March 2021 were configured with 100 ohm Pt RTDs. All new replacement RTDs are 1000 ohm Pt RTDs. If changing from one RTD resistance to another, you must change your RDE300 series configuration settings. See Changing RDE300 RTD Configuration (Pt100 / Pt1000).

If your RDE300 series unit does not have a connectorized RTD, follow the instructions below.

• WARNING: These steps involve access to an enclosure containing hazardous voltages and should only be performed by qualified personnel.
• Turn off power to the RDE300 series unit.
• Disconnect PV modules from the RDE300 series unit.
• Open the RDE300 series enclosure.
• Remove the existing RTD wires from the RTD channel to be replaced.
• Disconnect all connectorized cables on the PCB.
• Unscrew 4 corner screws and remove the PCB from the enclosure, taking care not to damage the PCB.
• Remove the existing RTD cable from the cable gland.
• Cut off the connector on the replacement RTD to expose the wires. Strip the wires.
• Insert the replacement RTD cable through the cable gland, extending far enough that it can fit behind the PCB after the PCB is returned to the enclosure.
• Install the PCB in the enclosure again and tighten 4 corner screws.
• Reinstall all connectorized cables.
• Insert the replacement RTD wires into the terminals where the old RTD was removed. Note the wire colors per the picture below. Match the Red and White wires to the picture. The middle wire may be either Red or Black, depending on the specific RTD used.
• Close and secure the enclosure.
• Reconnect PV modules to the RDE300 series unit.
• Turn on power to the RDE300 series unit.

NOTE: Older RDE300 series units shipped before March 2021 were configured with 100 ohm Pt RTDs. All new replacement RTDs are 1000 ohm Pt RTDs. If changing from one RTD resistance to another, you must change your RDE300 series configuration settings. See Changing RDE300 RTD Configuration (Pt100 / Pt1000).

Inside the RDE enclosure. 

RTD cables (white) enter the enclosure underneath the PCB and come over the gap shown at the top. RTD connectors for channel 1 and channel 2are on the right-hand side of the PCB.

Closeup of RTD wiring

Match the wire colors. The middle wire may be red or black.