Power Machines India Limited

The following parameters are monitored:

• Pressure and level of oil in accumulator tank;
• Oil temperature and level in sump tank;
• Water in sump tank;
• Position and proper functioning of unloader valves;
• Functioning of protective devices of motor starters;
• Discharge of water supplied to oil cooler;
• Control.

The automatic controls of oil  pressure system incorporate contactless sensors, logic and actuating  sections.

Various sensors convert monitored parameter values into corresponding electric signals (analog or discrete). The logic section develops output command signals to be applied to the actuating elements.

The whole logic section is located in a control cubicle which houses the modules. Each module is composed of printed circuit cards arranged in standard carriages.

Are intended for the turbines control by changing the opening of the wicket gates of Francis turbines, of  the wicket gates and runner blades of Kaplan turbines, and controlling use of needles and deflectors in Pelton turbines. The systems ensure automatic  maintenance of  the given unit rotation speed and prevent unit runaway at sudden load-offs.

Oil three-screw pumps are used in hydro-turbine oil pressure systems and also in sealing assemblies of ГАs-transfer sets for transferring oils having 0.2 to 3.5 St. viscosity.

Oil three-screw  pumps are used in hydro-turbine oil pressure systems and also in sealing assemblies of ГАs-transfer sets for transferring oils having 0.2 to 3.5 St. viscosity.

Distinctive features of pumps:

• Simple design combined with perfect technical characteristics;
• A possibility to use high-speed motors;
• Self-suction over considerable range of suction lifts;
• Noiseless vibration-free operation;
• Long-term service life with high efficiency;
• Convenience of erection and maintenance;
• Small overall dimensions.

Oil three-screw pumps are designed and manufactured of four types (series).

Thrust bearings with ftoroplasts coated shoes.

Hydrogenerators supplied by Power machinesare equipped with new-quality type of thrust bearings – the most reliable trust bearings in the world. The distinctive feature of the design feature of the design lies in the application of the antifriction layer on the basis of ftoroplast composition (polytetrafluorethylene) with the metallized spring liner for coating the thrust-bearing shoes.

The advantages of generator thrust beatings with such shoes are as follows:

• They improved  reliability and durability;
• They do not require the forced oil supply to the sliding surface;
• They have no restrictions on the operating conditions, including the startups and shutdowns, creep speed of rotation, rundowns without braking;
• They allow to increase the specific pressure up to 100 kg/cm ²;
• They allow to decrease the friction losses and oil reservoir dimensions;
• They do not require  the scraping of the surface in the process of erection and operation.

In addition to monitoring the turbine mechanisms, turbine automatic controls provide also the following:

• Water pumping out of the head cover;
• Control of oil transfer pump;
• Air admission when operating  in synchronous condenser mode;
• Air admission under transient operation conditions.

The following parameters are automatically controlled:

• Temperature of turbine bearing shells and oil;
• Oil level in turbine bearing reservoir;
• water discharge to oil cooler;
• Discharge and pressure of water supplied to turbine shaft seal;
• Water discharge through the turbine;
• Turbine bearing vibration;
• Condition of shear pins;
• Turbine shaft runout;
• Oil level in oil transfer tank;
• Power supply control;
• Position of locking devices;
• Level of depressed water in synchronous condenser mode;
• Pressure in maintenance seal.

The operation of turbine automatic controls is based on the same principles as the operation of oil pressure system controls. Various sensors convert the values of monitoredparameters of turbine mechanisms into corresponding analog and discrete signals coming in turbine automatic control cubicle (KAI).

If any of the monitored parameters is beyond the range of permissible values but the mechanisms still can operate, a warning signal is initiated. When the parameters reach their dangerous values, a command signal for automatic emergency shutdown of the hydro-unit is fed.

Turbine automatic control cubicle is similar to oil pressure system control cubicle: logic section forms output signals according to preset law to be applied  to the actuating mechanisms of turbine automatic controls.

The oil pressure systems are intended for feeding oil under pressure to hydro mechanical section of the governing system and also for control of the shut-off valves and the gate valves of irrigations systems and channels.

The main components of oil pressure system:

• Accumulator tank containing required volume of oil under compressed air.

• Oil pumping unit maintaining  effective volume and pressure in the accumulator tank.

• Controls of the oil pressure system.

The oil pressure systems are rated from 4 MPa and 6.3 MPa pressure.

Oil having 30 cSt viscosity at 50 degrees Celsius is used in oil pressure systems. Also such oil grades as Shell, Turbo oil 37”. “ESSO, Teresso 47’’, “Mobil, Dti Oil Heavy Medium” can be used. The above oils characteristics correspond to turbine oil.

The shut off valves are mounted on the penstock upstream of the spiral case and serve as an operating, emergency and maintenance shut-off device.

Electric-hydraulic control system provides automatic operating and closing of the shut-off valve during normal operation and shut off valve closing in case of emergency.

The oil for operation of the control system and actuating mechanisms is fed from separate or from turbine oil pressure system.

Shaft-off valves of two types are used:

• For heads ranging  from 45 to 230 m – butterfly valves
• For heads ranging from 170 m to 800 m – spherical valves.