19.08-13
AlphaStat-Plus Sensor Maintenance.
Lengthening AlphaStat-Plus Sensor Wire.
The sensor wire can be lengthened within certain guidelines. Poor connections or induced interference can
cause false temperature readings.
1. The sensor is not polarized- it can be connected either way around.
2. The wire normally used for sensor lengthening is twin 0.5mm
^2
stranded speaker wire.
3. Firmly attach wires to each other by either soldering (heatshrink over each joint) or by quality screw
terminals. Joins must be kept dry.
4. It is recommended that sensor leads be kept 300mm away from mains and comms cables.
5. Over 20 metres; extra care must be taken to avoid electrical interference being picked up.
6. In ‘noisier’ electrical environments screened cable may be required.
7. The absolute maximum cable length is 100 metres.
Replacing an AlphaStat-Plus Sensor.
If a damaged sensor needs to be replaced then the cover of the enclosure will need to be opened unless
the choice is made to join the wires externally (see “Sensor Wire Lengthening” section).
1. Remove the mains power supply, preferably remove the plug from the wall socket. Make sure no
other power source is feeding back through other connections.
2. Remove the 4 screw covers on each corner of the lid of the enclosure. This will require a fine tipped
tool such as a screw driver. Be careful not to damage the lid. Always press the tool away from you to
avoid injury if you slip.
3. Remove the 4 screws that hold the lid on.
4. Unscrew the damaged sensor from the terminal block.
5. Loosen the cable clamp for the sensor leads.
6. Carefully pull the wire back through the opening in the bottom case.
7. Thread the new sensor wire back through where the old one came from.
8. Place the wires of the new sensor into the terminal block where the old sensor came from and
retighten the screws.
9. Do not allow the sensor cable to come within 10mm of the high voltage connectors or components
inside the enclosure. Tighten the screws on the cable clamp.
10. Replace the lid, replace the 4 screws and tighten.
11. Push in 4 new screw covers available from your distributor or Senztek NZ Ltd. Note: there are
locating lugs to ensure correct orientation.
12. Reconnect the AlphaStat-Plus and turn on the power.
13. Check sensor is reading correctly and check AlphaStat-Plus operation as per “What You Should See”
section of this manual.
The table below has the correct resistance values of the sensor at different temperatures. The sensor must
be removed from the AlphaStat-Plus to measure these values correctly. Follow the above procedure for
removal of the sensor.
CAUTION: Dangerous Voltages may be present. The AlphaStat has no user serviceable parts.
Protective enclosure only to be opened by qualified personnel.
Remove ALL power sources before removing protective cover.
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A ‘short’ circuit can be caused by the sensor wires being
connected together. Check the wires are not partially cut.
and that moisture is not getting into the sensor causing cor-
rosion.
An ‘open’ circuit can be caused by the sensor wires being
broken. Check the wires are not broken and that moisture is
not getting into the sensor causing corrosion.
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