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Hydran* 201i Instruction Manual
3.4.2 Heating Plate
Heating resistors and a temperature-sensing thermistor are mounted on the heating
plate (item 2 in Figure 3-2). The power input to the heating plate is controlled by the
Hydran 201Ti and the aluminum cover (item 3 in Figure 3-1) acts as a heat radiator. This
allows the enclosure to maintain the temperature of the Hydran 201 sensor (and
electronics) between 25 and 50°C (77 and 122°F), regardless of the ambient or oil
temperatures. For details, see Section 3.6.
3.4.3 Hydran 201 Sensor
CAUTION
The Hydran 201 sensor (see Figure 3-3 above) consists of a brass body with the
following components:
• 1-in NPT (25 mm) conical threads at one end.
• The male cable connector, the oxygen breathing hole and the sensor's serial
number at the other end.
• On the top, a sampling port and a bleed screw allow easy sampling of the oil
for Dissolved Gas Analysis (DGA). The sampling port fits the Luer stopcock
valve of a syringe; this port is also used for purging during the installation.
• A thermistor is incorporated in the sensor's body to measure its temperature
and, using mathematical computations, compensate the effect of the
temperature on the detector's signal.
Combustible gases dissolved in the oil pass through a selectively-permeable
membrane into an electrochemical gas detector (located inside the H201 sensor). Within
MA-033
Rev. 14.0, 12-Nov-18
Mishandling of the H201 sensor (such as a perforation or
scratch on the membrane or subjecting the sensor to paint or
solvent) voids the warranty.
Figure 3-3: Hydran 201 Sensor
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