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Under the circumstance of oil dielectric loss ≥ 0.01%, with oil
cup, positive wiring can be used to measure the dielectric loss of
oil.
This following protection features are not included in this
instrument:
• High voltage short-circuit protection
• CVT over-voltage protection
• Poor grounding protection
II. Operating principle
Under the AC voltage, the dielectric would consume a part of
electrical energy that would be converted to heat energy leading to
loss. This kind of energy loss is called the dielectric loss. When AC
voltage is applied to the dielectric, phase-angle difference Ψ exist
between the voltage and current of dielectric. The δ which is the
complementary angle of Ψ is the dielectric loss angle. The tgδ
which is the tangent of δ is dielectric loss tangent. The value of tgδ
is the parameter for measuring the dielectric loss. The measuring
circuit of the instrument includes a standard loop (Cn) and a tested
loop is (Cx) which is shown in Figure 1. Standard loop is composed
of built-in high stable standard capacitor and measurement circuit.
The tested loop is composed of specimen and measurement circuit.
