The induction generator (IG) never trips due to steam load fluctuations unlike an alternator.The power generator will vary in proportion to the steam flow rate. If the steam flow rate falls below a critical value ( < 20% of the designed value), the IG will go into the motoring mode.
Induction generators continue to operate in spite of large fluctuations in the steam inlet pressure unlike an alternator. The power generator will vary in proportion to the pressure at the inlet. If it falls below as critical value (<50% of designed value), the IG will go into motoring mode.
As long as the DG governor is stable and the DG power rating is at least 30% more than the IG.
Gear Box Module:25%
Controls and instrumentation:10%
Mounting skid and miscellaneous:10%
Power factor will be corrected at site depending upon the client’s existing capacitor bank and existing power factor. Optional we will provide banks of 10KVAR and keep adding as necessary at the time of installation, to bring the PF better than 0.85 lag.
For saturated steam applications, no particular care is needed as all the dissolved salts will be in the boiler. If it is good for the boiler, it will be acceptable for the turbine also. Further since we are using hardened stainless steel for the turbine, effects of erosion and corrosion are minimal. In case of super heated steam, silica content needs to be monitored closely (less than 1 ppm).
At least 15 years, since we are using hardened stainless steel for the turbine rotor.
It is estimated to be 3 years or more, with an annual inspection.
We recommended the following :
Bearing and seals : Annual inspection and change, if necessary
Lube oil change : Every three years
Some fast moving and low cost spares like oil filters, gaskets, relays, etc. will be handy and the same will be advised during installation.
It is advisable to order one set of bearings and seals along with the turbine.
It is expected to be 15 years since we are using hardened stainless steel for the turbine rotor. However, adequate care is to be taken to ensure that only dry steam enters the turbine and this can be simply accomplished by installing an efficient moisture separator (with thermodynamic trap) and a Y-strainer in the inlet line to the turbine. This is not included in standard scope of supply.
Whenever an induction motor is run higher than its synchronous speed by the help of a prime mover it starts generating power instead of absorbing power. All induction machines always operate at a lagging power factor (i.e. the current vector lags the voltage vector and the cosine of the angle of the lag is defined as the power factor). The power factor depends on the slip, which is a function of the loading of the motor. The lag angle will be 90 deg. when the machine runs at zero slip, that is at synchronous speed and this is known as quadrature. At quadrature, it will neither absorb nor generate power. If with the help of a prime mover, the angle increases beyond 90 degrees and the power factor is negative, which means the machine is generating power. The power factor is adjusted by adding the required KVAR capacitor bank. Since the excitation of the IG is from the grid, it does not require any governing. Grid acts as the governor. Also it does not call for synchronizing as it automatically locks itself to the grid.
ECT is wired to shut down safely in any of the following undesirable operating conditions:
High lube oil temperature
Low lube oil pressure
Low instrumentation air pressure (to valve actuator)
Over speed (which is unlikely)
High core winding temperature
The trip will be annunciated and a hooter will come ‘ON’ and one has to inspect before restarting.
In addition an emergency trip (Mushroom button switch) is also provided.