Water turbines of Wiegert & Bähr
Wiegert & Bähr is one of the best producer and manufacturer of hydro turbines. The company is well known for excellent quality turbines made in Germany for nearly 50 years.
All types of Water turbines
Scope of production:
All types of water turbines, like Pelton turbines, and Francis turbines. Furthermore Kaplan turbines and Crossflow turbines are produced for worldwide projects. In the factory in Germany is produced the Pelton turbine and the horizontal Francis turbine also the horizontal Kaplan turbine and the vertical turbines.
Water turbines and governors
Governors: The turbines are controlled by hydraulic governors. Wiegert & Bähr is known for best quality governors. The company also makes electronic turbine governor, speed governor for hydraulic turbines and level governors for parallel and isolated operation from the grid. The turbine governors are produced in Germany. A water turbine governor consists of a level sensor in the water intake and a long transmission line and an electronic module inside the low voltage control cabinet.
Switchgears and controls
The electric switchgear and supervision system is manufactured in our own works and installed at site by our own specialists.
The electric commissioning engineer runs the full test program during getting the installation into operation. He needs the maximum water flow available for several hours to make all adjustments of the electronic control equipment.
Water level measuring
The water level pickup sensor may be of the capacitive type or of the inductive type or working with ultrasonic electronics. It measures the water level accurately and is also used for the control of the cleaner.
Trashrack and trashrack cleaners
Trashrack cleaners are produced in our hydraulic workshop. Then they are installed in the water intake. Installation and commissioning is done by our own specialists.
Water turbines and turbine materials
Turbines are made of steel, mild steel, or stainless steel. Sometimes they are made of nodular cast iron or welded steel. Copper, and gold as well as silver are usually too expensive. Other materials like bronze and aluminum are used for equipments only.
Water turbine protection against corrosion
Water turbines are painted in red and blue colors. Green and white colors as well as infrared and brown are rarely used. Other materials are not used.
Water turbine regulator
The water turbine regulator acts on the guide vanes. They are also called wicket gates. Double regulated turbines such as Kaplan turbines have a runner with adjustable vanes to direct the water flow und to drive the turbine opening for a maximum of total output.
The mechanical output and the electrical output are not the same. An efficiency maximizing module is included in the PLC which is the programmable logical control system. Often a SCADA system is included, sometimes also a remote control system. The data acquisition and transmission system needs a telephone line or a GSM connection and is able to transmit values by wire and wireless. Also remote control and monitoring is possible. Local control is done from inside the power house or outside of the powerhouse or from the power plant which is also known as the hydro power plant.
Inside the power house
Inside the hydropower station you find the water turbine arrangement with generator, coupling hydraulic brake, and synchronous generator. Sometimes there is an induction generator called asynchronous generator. Only the synchronous generators have power factor control, or power factor controller which is called AVR, automatic voltage regulator.
Types of excitation
Modern generators have brushless excitation. Static excitation is used for low voltage generators. Medium voltage generators and high voltage generators have an over speed protection. Sometimes they have thrust bearing in the radial bearing and overhang design and manufactured overhead mounted runners.
Maintenance of water turbines
Most are of horizontal axis. Vertical axis and tilted penstock including civil works with the transformer can be found. The high voltage switchgear of high output and generator shaft with magnetic inductive pick-up are loved by operators. Butterfly valve, gate valve and spherical valve with dead weight closing or counter weight closing are equipped with flywheel and circuit breaker.
Cables and the local project management confirm the civil structure and the power house elevation. Sometimes the pressure rise causes a water hammer in the penstock. The forebay is not important for the spiral casing. But it is of wear resistant steel with a reduction piece in between.
The painting system with companion flange, water filter, and pressure gauge often is connected to the draft tube with pressure indicator. The black start capability needs droop adjustment at the DC-converter. A modern type of level control with surge arrestor and casing of metal bearings, maintenance free may be found.
The foundation material with bypass and filling valve or pipe connection, not erection and commissioning, but with self-regulating brushless alternators is most suited in many cases. The insulation class auxiliary winding is missing.
Stator, stator core pack, winding head and rotor are dynamically balanced. The revolving field copper damping cage as well as the sleeve bearings with foundation frame, are connected by anchoring bolts to take centrifugal force together with moment of inertia to the rotation speed.
The run-away-speed is high. The oil supply is coupled to the speed transmitter and later to the terminal box. Current transformer and related voltage transformer or if so called the potential transformer are used for temperature monitoring.
Nuclear power stations with all their risk as seen in Japan speak a clear language towards hydropower. Anti-condensation heater with diode monitoring system and neutral grounding are sustained by 3-phase short current values.
Reactive power transmission and bump-less changeover
Reactive power and transmission systems to special water turbines need synchronizer, potentiometer, and rheostat for cold resistance measurement.
Voltage and Power
In the stations you find high voltage generators and residual voltage. Under-speed protection and over-speed protection are used for surface conservation. The documentation concerns prime coating with surface cleaning synthetic resin observing instructions.
The single line drawing is made after the factory test report when the earth fault protection is ready. In any case of breaker failure, be it differential protection relay or load imbalance relay. The vector surge relay gives alarm to the generator management relay. The phase-balance relay indicates the feeder relay to the control panel via grid protection. The fault display is protected by a fused circuit breaker with battery charger and decoupling diode.
High speed Francis runner:
The high speed Francis runner is in opposite to the low speed Francis runner coupled to a transistor inverter via cable bridge and operator panel. Often the visualization display and the excitation of the system is governed by remote access. The complete hardware configuration at the station service transformer with it’s accessories is related to the installation material.
Transformer and emergency generating system both connected to the Turbo Diesel exhaust cleaner, have their own tools. Last not least erection and commissioning for documentation and delivery mainly for manufacture in the workshop are test stand designed.
The test field with dowels, screws, and washer are used for bolts with stay rings on steel plate and layer. The branch pipe operates the nozzle and the bucket. The needle actuates the spear valve deflector draft tube according to the Winter-Kennedy measuring principle. As another measuring method the thermodynamic measurement is quite often used.
The heat measurement is related to the water consumption and air consumption. But the cooling air is related to the base frame via one vibration monitor. The vibration probe with the vibration sensor is protected by the energy supply. The complete grid voltage and the grid frequency of small hydro and micro hydro system is not high. The mini hydro power station often includes a micro turbine or a mini turbine with hydroelectric fish-protection.
The hydraulic structure consists of concrete structures with reinforcement iron. Drill holes are brought into the wall. The thickness of the welding seem is tested by ultrasonic test or by radio-graphic method. The generator impregnation is made of high wear resistant resin.
Is hydropower a good investment?
If you think of all the risk of other electric power production such as steam turbines fired by coal, gas or crude oil the water turbine is a smooth way to make energy. There is no combustion, neither of sustainable materials, nor of non sustainable material, nor of biomass. For this reason it is a very clean energy. Even in case of an accident the risk of fire is negligible. There is no noise and heat pollution to the environment.
Why go for regenerative energy?
Resources of all other kind are not available for ever. To make sure a future to our children we have to save resources wherever it is possible. Water is available in every country. Environment protection therefore is not only a word but a challenge to all human beings. Wind energy is easy to harvest but there is nearly no way to make a forecast of the wind power produced the next day. Hydropower instead is known best and the production even of the next week is easy to forecast.
Runners are made of one piece stainless steel, cast in one single procedure. Pelton runners are often made of a forged hub and welded buckets. The complete runner is balanced in two planes a so called balancing of rigid rotors. Hydro turbines usually are not high speed balanced.
The runner material is often enhanced by a glass ball hardening. With this hardening procedure the material is mechanically reinforced beyond the surface. And it is of higher wear resistance with increased lifetime. Repair welding is done on the runner sometimes. Usually the turbine runners are assembled to the generator shaft without an own bearing assembly. The cooling of the bearings is managed by oil and the oils is cooled by water in a separate cooling loop. Monitoring of the temperatures is done by PT 100 or PT 1000. Thermistors are only used for smaller generators for winding protection.
The electric measuring, supervision, monitoring and protection is done by a couple of specialized measuring facilities. The monitoring relay is installed in a low voltage control cabinet and the medium voltage switchgear is installed in an own cabinet. Transformer protection relay such as the Buchholz relay protect the transformer against serious damages. Diesel generators shall make emergency power production if the turbine unit is unable to operate due to standstill in maintenance or repair.