810-1902-03 Rev D TM1 Installation Guide
3
System Description
The TM1 measures hydrogen using a patented, solid-state sensor made of Palladium. The sensor is
in direct contact with the transformer oil; neither gas extraction nor membranes are utilized. An electric
potential is applied to the palladium sensor. When hydrogen from the oil contacts the sensor, the
electrical properties of the palladium sensor change, resulting in a change in the electrical output of the
sensor. This electrical change is proportional to the concentration of hydrogen in contact with the
sensor and is reported as ppm H
2
. Using the ppm results, ROC is calculated and reported in units of
ppm/day.
The temperature of the measurement environment is precisely controlled in order to ensure stable
readings. The TM1 will make one measurement approximately every 30 minutes. The exact time
between measurements is a function of the temperature of the incoming oil. Therefore, the time
between measurement results may vary slightly.
TM1 data is stored onboard in non-volatile RAM. At least two years’ worth of the most recent data is
stored. Once the available memory is full, data is overwritten in a first-in, first-out manner. Several
communication options allow for the transfer of data in near real-time, or discrete batch download of
data is available via the USB port.
The major components of the TM1 include:
H
2
Sensor – Palladium sensor selective for H
2
gas
Oil Circulation System – utilizes a patent-pending design that eliminates the need for a reciprocating
or positive-displacement pump. More robust in design, the auger-style TM1 pump is used to
provide a representative oil sample at the sensor.
Heater – provides thermal control of measurement environment
Electronics – power supply, analog inputs and outputs, alarm relays, system board and
communications ports
Enclosure – IP66 /NEMA 4X rated enclosure with integrated sunshield
Transformer connections – 1½” NPT valve (can be adapted to other sizes), power and
communication wiring glands, bleed port.
Display – Touch activated. Displays hydrogen level, hydrogen rate of change, alarm status, and
service status.
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