Computation and design of ac shunts for testing commutation equipment

Conclusions

The shunt errors were measured on an ac potentiometer type R-56. The voltage terminals of the shunt were connected to the measuring terminals by means of a twisted pair. These tests led to the following conclusions:

the resistance of the shunt amounts to 119.6μ ohm, which differs from the calculated value only by 0.33%; the time constant of the shunt amounts toωT_s=0.835·10⁻², which satisfies (9).

It is possible to conclude from the measurement results that the shunt can be used for measuring short-circuit currents with an error not exceeding 0.5%.

The shunt was tested for thermal stability by passing through it 30 ka for 0.3 sec. The rise of temperature in this test did not exceed 100°C, which is below the calculated value. This circumstance is due to the fact that the shunt is short and a considerable effect is produced by the dissipation of heat away from the manganin strips in the butts and massive busbars.

The shunt was extensively used in the commutation equipment laboratory of the Leningrad branch of the V. I. Lenin All-Union Electrotechnical Institute in testing high-tension equipment with satisfactory results.