Hydran* M2-X Instruction Manual
Page 32
MA-029
Rev. 1.0,
30-Jul-18
2.
Sampling port
: See the bleed screw (item 3 below). The sampling port fits the
Luer
stopcock valve of a DGA syringe.
3.
Bleed screw
: The bleed screw and sampling port (item 2 above) are used to
purge the
air from the sensor during the installation and to sample oil for
Dissolved Gas Analysis (DGA). The oil sampling procedure is described in
Appendix J.
4.
1.5-in NPT male threads
: They are used to mount the Hydran M2-X directly
on an
open-bore valve of a transformer or any other oil-filled electrical
equipment. The gas detector and moisture sensor are both mounted inside
t
he sensor’s threaded extremity.
5.
Sensor’s serial number
: The serial number is also specified on the Test
Certificate
and Data Sheet (for an example, see Figure 3-12). Sensors are
identified with a serial number as each one is unique and comes with a
different set of calibration parameters.
Note: Each Hydran M2-X is configured for a specific sensor. If several Hydran
M2-X
’s are received, take the necessary precautions not to swap the sensors
and Hydran M2-X
’s.
6.
Connector:
To link the sensor to the electronic card cage.
7.
Breathing hole
: Air penetrates through the watertight membrane vent (see
item 5 in
Figure 2-3) and inside the Hydran M2-X, and the breathing hole
allows the air to reach the gas detector (inside the sensor). The gas detector
requires air to work properly.
8.
Twist-and-lock mechanism
: This twist-and-lock feature is no longer used to
attach the Hydran M2-X enclosure and the sensor together. This has been
replaced by a clamp mechanism. Refer to Figure 4-3. The Hydran M2-X
enclosure can be replaced without removing the sensor from the valve.
2.4.2
Measurements Performed by the Sensor
The sensor continuously makes three measurements:
•
Gas level
: Gas detection is based on combustible gases dissolved in the oil
passing
through a selectively gas-permeable membrane into an
electrochemical gas detector (located inside the sensor). Within the gas
detector, the gases combine with oxygen (from ambient air) to produce an
electrical signal that is measured by an electronic circuit and converted to
ppm. The gas detector is sensitive to the gases that are the primary
indicators of incipient faults in oil-filled electrical equipment:
–
Hydrogen (H
2
)
–
Carbon monoxide (CO)
–
Ethylene (C
2
H
4
)
–
Acetylene (C
2
H
2
)
•
Moisture level
: Moisture detection is performed by a thin-film capacitive
moisture
sensor. The capacitive value of this sensor varies according to the
moisture level. This value is converted to an electrical signal that is
digitalized for reading by the CPU.
