The project is to upgrade a hydro synchronous generator 50 MVA, 24 poles, 3-phase wye, 13.8 kV L-L, lap winding, 2-turn/coil, 2-circuits, 198 slots. The upgrade shall include the rewind and to replace the stator core. The new rating shall be 60 MVA. The alternatives for the rewind are one turn...
This question came up during the rewind of a 13.8 kV machine 40 MVA, Hydro. The new bars were elongated by about 6 inches. As a result the air baffles (covers) became closer to the overhang portion of the bars which reduced the clearance between the live parts and the covers. The Contractor...
In the rewinding and uprate of a 40 MVA (uprate to 46 MVA), 13.8 kV, 3-phase, 60 hz, one circuit, wave winding, hydro generator, the mean length turn has increased to achieve bar end arm and cross over clearances of 1/2". This resulted that the overhang portion of the bars (winding) was...
This subject is about the practice of using six wire dual element RTDs, copper (10 ohms) and platinum (100 ohms) Resistance Temperature Detectors (RTDs) placed at two different axial locations in the stator slots between the top and bottom bars.
The new trend is to use only platinum because of...
The series connectors are the parts that connect, in series, two coils by brazing them between (or inside)the connectors. This practice is used on the stator coil winding connections. The series connectors are carrying the same amount of current as the coils. Therefore, it is assumed to be sized...
This subject is about the minimum spacing between the bar end arms and the minimum clearance at the first crossover bar behind the top bar on a 13.8 kV rotating machine, 3 phase wye connection, NEMA Class F insulation, air cooled hydro generator. Some specifications for the stator rewind asked...
How do you size a three phase 480 volt gen-set in KVA (KW) based on loading only one phase of the gen-set? The current required to perform the core loop test (in this case) is 615 amps single phase at 480 volts.
Appreciate your expertize and valuable responses.
Does the Differential Relay operate with zero current from on side and no internal fault?
Three single phase Generator/Transformer differential relays with percentage and harmonic restraint. They are GE model 12BDD15B relays. Tap setting is 2.9 Amp, zero restraint pickup 0.87 amps, 25% slope...
