The DTT7031 is a biased three phase differential relay designed to protect high voltage transformers against internal faults. Its very rapid operation limits the damage due to short circuits between phases, between turns on the same phase, or between windings and earth/ground if the earth/ground currents can attain relatively high values.
The DTT7031 is supplied in a plug-in modular case type R4.

PROTECTION   Functions

• Differential Protection [87]

Functionalities

• Differential Unit Settings: Low threshold: 20-50% In; High threshold: 5-20 In
• Trip time: Low threshold: 50msec; High threshold: 40msec
• 2 output units
• Mechanical operation flag with hand reset