MA-041
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DGA 900 Plus - Installation & Commissioning Manual - Rev 1.1
4-Mar-22
Page 17 of 99
6
CARD OPTION #1: THERMAL MODELS
The thermal card option generates the base models relating to thermal and moisture
readings. It integrates data from the existing DGA analysis (for moisture and ambient
temperature) and accepts inputs from two 4-20 mA inputs to obtain top- and bottom -oil
temperatures (see Section 6.3) and up to three split core CT sensors for transformer load
(see Section 6.4).
6.1
Sensor Input Configuration
Table 6-1 lists the types of inputs used by the Thermal Models.
Table 6-1: Thermal Models inputs
Input
Label
Sensor Type
AIN 1
CT H/H/A/H
CT
AIN 2
CT X/X1/B/C
CT
AIN 3
CT Y/X2/C/Y
CT
AIN 4
Top Oil Temperature
4-20 mA
AIN 5
Bottom Oil Temperature
4-20 mA
AIN 6
spare
None / CT / 4-20 mA / RTD
DIN 1
spare
12-24 V
DIN 2
spare
12-24 V
DIN 3
spare
12-24 V
Note:
The default range for the Thermal CTs is 0-5 A. Other ranges are available on
request with advance notice.
Thermal Models requires the installation and wiring of up to three CTs and two
temperature sensors provided with the Thermal Models pack. These are to be wired as
shown in Figure 6-1
and in accordance with the ‘MA
-024
–
DGA 900 Installation Manual’.
The Top Oil Temperature sensor should be installed in a vertical position on one of the
long sides of the transformer, typically between 20-30 cm from the top, and horizontally
in the middle. The Bottom Oil Temperature sensor should be installed as per the Top Oil
Temperature sensor, but 20-30 cm from the bottom.
6.2
Wiring
The wiring for the Thermal Models is shown in Figure 6-1. Wetting terminals accept up to
14 24 V DC connections with a cable cross section of 0.14 mm² to 2.5 mm², AWG: 14
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26.
