WKV G E N E R AT O R S
We are only the caretakers of the world and its resources that we pass on to our Children. WKVâ€™s company slogan
History of the Company
A Sustainable energy policy, based
on renewable resources, will be
WKV is one of the leading manufacturers of small- and medium-sized hydropower plants worldwide.
crucial to a livable future for the coming generations. Hydropower is one of the front-runners amongst such renewable energy sources. As a leading supplier of technology
It all started in 1979 in the barn of the Gernhansen Farm in Simonswald (Southern Black Forest, Germany) where the first hydropower plant was designed and built. The small company grew steadily thereafter to become a limited liability company in 1986, and finally to evolved into a Joint-stock company in 1997.
and equipment for small and medium sized hydropower plants, WKV have decided to make a significant contribution towards the future of sustainable energy.
Throughout its 30+ years history WKV have installed hundreds of small and medium sized hydropower plants, in more than 40 countries around the world, producing environmentally friendly power in Europe, South and Central America, Africa and Asia. At this point, WKV intends to focus not only on the manufacturing of equipment, but also increasing its operations and facilities in Germany as well as elsewhere in the world. The “Zukunftsfabrik”, the state of the art factory of Wasserkraft Volk AG in Gutach started operations in May 2000. It is the
first heavy-duty manufacturing facility in Europe, which works totally energy selfsufficient and without any CO2 emissions. With the rapid progress made in a short period of time, we realized the need for increasing our capacity. As a result in 2008 / 2009, at a time entire market was confronted with the economic recession, we took up a challenge to build up the most modern and highly efficient factory covering 4000 m 2 that was designed and now taken into operation: The “Energiefabrik”. Besides hydro turbines and of course alternators for hydro power systems, all other kinds of alternators for a multitude of applications and prime movers are manufactured by WKV. Product quality, reliability and flexibility associated with excellent customer support are main features of our operation. As a medium size enterprise, we deliberately focus to Germany only as the location for our factories in view of our social responsibility and obligation towards the country and future generations. Last but not least, a great portion of our success comes from our highly motivated, dedicated, devoted and committed work force receiving consistent advance training, education and up dating in their respective fields in order to render a reliable and persistent service to our customers.
Drawing right side: The WKV Turbine Factory (blue) and the Alternator Factory (red) Picture left side: Manfred Volk, founder of the company
The basics are unchangeable. Physical laws are permanent. Vital is to make the best out of them.
Θ H= – l
B= – A Θ =Ι·N
F = m· a U Ι= – R
Highly skilled and talented team of engineers, designers and technicians at WKV are marching towards efficient and innovative solutions through mere dedication and devotion. Besides optimizing the alternators electromagnetically and dynamically, our main aspiration is to provide a perfect fit to the needs of our customers in terms of electrical and mechanical characteristics. Sophisticated production technology and the knowhow of our work force helped guarantee timely delivery of reliable products of highest quality. We are combining the most modern production technology with a solid input of manual work because: Quality can just be planned, but finally it has to be realized by the factory!
Rotor winding machine suitable for rotor weights up to 20 tons
1. Technical brief description Brushless 3-phase synchronous alternators series "G"
Design according to: EN 60034-1 VDE 0530-1 IEC 34-1
See table 1 PF = 0,8 (range 0,8 lag. – 1 – 0,95 lead.)
Rated voltage: Frequency: Cooling air temperature: Installation height: Enclosure: Cooling method: Mechanical design:
Output range / kVA
The below rating chart is based on VDE rules. Rated output: Power factor:
400 V ... 15 kV (see table 1) 50 Hz / 60 Hz 40° C 1000 masl See chapter 3 See chapter 4 See chapter 5
1000...7000 1500...8500 2000...10000 4000...20000 4000...16000 6000...22000
x x x x x x
Voltage range 400 V, 480 V 660 V, 690 V, < 1000 V 2,1 – 4,16 kV 6,0 – 6,9 kV 7 – 11,5 kV 11,6 – 13,8 kV 15 kV
x x x x x x x
x x x x x x x
x x x x x x
x x x x x x
x x x x x
x x x x x
x x x x x
x x x x x x x
x x x x x x x
x x x x x x
x x x x
Speed range The alternators can be designed according to all international standards like BS 4999, IEEE, NEMA MG1 etc. For marine and offshore application, design and manufacturing according to all international classification society rules such as ABS, BV, CCS, DNV, GL, LRS, MRS, RINa etc. is offered.
4-polig 1500/1800 min -1 6-polig 1000/1200 min -1 8-polig 750/900 min -1 10-polig 600/720 min -1 12-polig 500/600 min -1 14-polig 429/514 min -1 16-polig 375/450 min -1 18-polig 333/400 min -1
x x x x
Table 1: Rating overview
Alternative mechanical and electrical design is always welcome and possible on request.
2. General design The alternators basically consist of the main internal-pole generators and the external-pole exciter machine. An auxiliary winding within the main stator slots performs the power supply to the automatic voltage regulator.
2.1 Stator The stator housing, which is of welded construction, contains a stator core made up of low-loss laminations, pressed together by means of pressure plates to form a compact unit. The stator insulation system is based on temperature class “H” materials for low voltage alternators and class “F” for medium voltage alternators, according to EN 60034-1/ VDE 0530-1. The winding overhangs and connections are supported by fastening elements and firmly linked by mechanical means to guard against loads caused by electro-dynamic forces. The exciter machine stator is fixed in the non-drive end bearing housing.
2.2 Rotor The main salient-pole rotor is made up of steel laminations or steel plates that are hydraulically pressed together. A copper damper cage, electrically interconnected to the pole shoes and from pole to pole, is installed as standard. The main salient-pole rotor winding is made from copper profile and protected against deformation caused by centrifugal forces by suitable and generously sized spread supports. The exciter rotor consists of dynamo lamination with the three-phase winding incorporated into its slots. The rotor windings comply with temperature class H in accordance with DIN EN 60034 - 1 and VDE 0530 - 1. Standard balancing of the rotor is performed according to EN 60034 -14 with half key. Other shaft designs can be supplied at customer’s request. 2.3 Bearing housings The bearing housings are made of rigidly welded construction with integrated machine feet, in order to ensure a perfectly stiff fixing to the foundation. 2.4 Bearings Antifriction bearings are used at frame sizes G11 and G12 as a standard. At the driven end, we use re-greasable roller bearings with grease regulation, and at the non-drive end ball bearings or a combination of ball and roller bearings are used.
For frame sizes G13 – G14 – G15 – G16, generally sleeve bearings with loose oil rings are used. Depending on operation and turning speed, separate cooling by means of water-cooling snakes or separate oil supply might be required. Also the small frame sizes can be performed with sleeve bearings on request, and all frame sizes are possible with pedestal sleeve bearings if required. For safety reason during transportation, all sleeve bearings are delivered without lube oil. 2.5 Terminal boxes Connection boxes for power termination are usually located on top of the NDE bearing housing at IP 23 generators or on the side of the NDE bearing shield at totally enclosed alternators with top-mounted coolers. Enclosure type for all terminal boxes is IP 54. The main terminal box is performed with 4 studs: 3 terminals for power connection L1–L2–L3 and 1 terminal for neutral connection. The neutral point is connected of the 3 neutral side winding ends after passing the neutral current transformers that are usually included for measuring and /or protection features. If required, the terminal box can be modified for housing further CTs or VTs. All low voltage and signal connections are performed in an auxiliary terminal box located at the frame side.
3. Enclosure type (EN 60034-5 / VDE 0530-5)
Examples for standard cooling mode
Standard design is IP 23. Application of air inlet / dust filters as well as higher protection mode as IP 43, IPR 44, IPR 54, IP 44 and IP 54 etc. are possible on request. IC01
4. Cooling mode (EN 60034-6 / VDE 0530-6) Examples for standard design Standard design is IC 01, direct air-ventilated. IC31 (cooling air channel connection), IC0161 (top-mounted air-to-air heat exchanger), IC8A1W7 (top-mounted water cooler) or other solutions can be offered on special request. IM1001
5. Design (EN 60034-7 / VDE 0530-7) The basic design modes are IM1001 (B3) and IM1101 (B20) for horizontal mounting and IM 3011 (V1) for vertical mounting.
Principally we confirm for WKV alternators: Every requested design our customers need is possible! 9
6. Electrical performance, brushless excitation, function 6.1 Alternator The auxiliary winding, via the AVR’s control circuit, feeds electrical energy to the exciter winding of the exciter machine. The exciter power, transformed to the 3-phase rotor winding of the exciter machine, is converted to DC power and
supplied to the rotor of the main generator. Using permanent magnets that are located in the stator of the exciter machine ensures the self-excitation of the system. Adjusting the exciter current in the main rotor, using the control circuit of the automatic voltage regulator, performs the voltage regulation of the main generator output.
1 3 5
Automatic voltage regulator
Auxiliary winding 1
Exciter field current
I /O Terminals
Rotor winding I
V6 Exciter rotor u
Exciter field winding
See AVR description for pin configuration
K1 e. g. Voltage setting PF setting De-excitation
Basic circuit diagram for alternator series „G“ 10
The impregnation plant in Gutach/Germany equipped with both horizontal and vertical pressure tanks and with ovens where the components are turned during drying-out is one of the most modern and capable workshops of its kind worldwide.
6.2 Automatic voltage regulator (AVR) Basically, a digital automatic voltage regulator (AVR) â€žABB Unitrol 1000-7â€œ or approved equal is used. The AVR shows, among others, below listed functions: Voltage regulator with PID control algorithm Cos phi and reactive power regulator with PID control algorithm Excitation current regulator (manual control) with PI control algorithm Various limiting and protection functions Commissioning and maintenance software CMT 1000 Optional functions are: Modbus serial communication Reactive power sharing between parallel machines by RS 485 bus Voltage matching prior to synchronizing Automatic synchronizing Synchrocheck function Monitoring of rotating diodes Power System Stabilizer, acc. to IEEE PSS 2A/2B The AVR is mounted into the auxiliary terminal box of the generator but can also be delivered lose for location into the control cubicle. If requested, we are also prepared to use any other approved AVR system or to deliver a special exciter data sheet along with the alternator, so that our customers are enabled to use their own AVR system.
Picture left side: Final alternator assembly
7. Operating performance, characteristics
7.2 Static voltage performance The static voltage performance/regulation accuracy is ± 0,5 % ... ± 1 % at: no load up to rated load, PF = 0,8 - 1 cold and warm generator speed drop of about 3 %.
7.1 Voltage adjustment and operating range The output voltage is continuously adjustable by ± 5 % (according EN 60034) of the rated voltage for rated operation, using a voltage setting potentiometer of the AVR software. An increased voltage setting range is of course possible for special application, by special design of the machine. For testing or synchronizing purpose, the setting range is increased to ± 10 %. The voltage operating range according to EN 60034 is (0,95 ... 1,05) x rated voltage between no load and full load, considering limitations as set by the EN rules. Various grid codes (special rules for voltage and frequency stability of some mains operators) can be considered by special design if requested.
7.3 Transient voltage performance Magnetic circuit and windings are optimized for low voltage transients. Usually, the transient voltage dip at rated load connection is below 25 %, the transient time until reaching rated voltage is around 0,5 s. Machine size and speed have an influence to these values. Exact values are calculated and documented based on project needs.
5 0 -5 -10 -15
Usually, the winding layout is based on minimizing of the 5th and 7th harmonics. By use of the so-called “2/3 winding pitch” also the 3rd harmonic can be eliminated, especially for low voltage alternators that shall be operated with low-resistance neutral grounding.
0,8 0,7 0,6 0,5 0,4 0,3
Load shedding / connection in [%] of rated load
Underexcited 1 p.f. 0,8 p.f. 0,4 p.f. 0,1 p.f.
Reactive load (p.u.)
Active load cos phi 0,95 cos phi 0,9 cos phi 0,8 cos phi 0,6 cos phi 0,4 cos phi 0,2
Load shedding / connection in [%] of rated load
Telephone Harmonic Factor “THF” Values as per EN 60034 are easily undercut Harmonic content Values between phases < 2 % at no load up to rated load and PF = 0,8 ... 1 With linear and symmetric loads.
Performance Characteristic / Capability diagram
Active load (p.u.)
Transient voltage drop drop / /rise [%] Transient voltage rise [%]
Transient voltage behaviour
7.4 Voltage waveform Optimization of the geometry of the stator magnetic circuit leads to a sinusoidal voltage waveform. Characteristics are defined by:
7.5.1 Unbalanced loads Alternators of series “G” are suitable for single-phase loading, without loading the other phases, up to: 60 % of the rated current between Ph-N 35 % of the rated current between Ph-Ph A relation between counter system current I 2 and rated current I N 20 % of max. 20 % is permissible, what is more than required by EN 60034. Every non-symmetric load causes a voltage asymmetry: dU approx. ± 6 % at 60 % current Ph-N dU approx. ± 4 % at 35 % current Ph-PH To avoid additional losses especially in the damper cage, the loading should be as symmetric as possible. In case of mixed unbalanced loads (other phases also loaded with different currents) the actual alternator load has to be analytically or graphically calculated using the so-called Symmetric Components. Generally, in no phase the rated current shall be exceeded and the relation I2 / IN shall be less than 20 %. WKV recommends a limitation of I2 / IN < 0,08 as required in EN 60034.
7.5.2 Overload As per EN 60034 1,5 x rated current for 30 sec. In addition, fitting to the performance of reciprocating engines, 1,1 x rated current for 1 hr every 6 hrs is possible. Furthermore, 1,8 x rated current for approx. 10 sec are suitable, e.g. for motor starting or switching sequences.
by proper machine and AVR layout at min. 3 x rated current for max. 10 sec. Other values are possible on request.
7.5.3 Short-circuit current WKV alternators are short circuit-proof. The initial short-circuit current is limited by proper layout of the influencing parameters. The decay time of the initial to the sustained short-circuit current is 0,3 ... 0,6 sec, depending on machine size. The sustained short-circuit current is guaranteed
7.6 Non-linear loads Polluted networks and static converters as consumers with non-linear currents are causing voltage harmonics as a reaction. For minimizing the additional losses within the alternator and for granting proper function of the consumers, high value is set on lowest-possible voltage harmonics. One important pre-condition for that is a small sub-transient reactance Xd”. WKV therefore shows high flexibility and complies with project-specific requirements, in order to reach balance between passably big short-circuit current and the needed voltage values, for realizing the overall conditions as required by the project.
Short Circuit Current Characteristics 4,0
Short-circuit current [kA]
7.5 Electric currents
8. Parallel Operation 8.1 Tolerances for synchronization The below listed conditions shall be met: Max. voltage gap: 5 % of U N Max. frequency gap: 2 % of f N Phase sequence and phase angle shall match Bigger voltage and frequency tolerance as well as special design for operation with big additional flywheels shall be separately discussed prior to offering. 8.2 Load sharing at stationary operation The distribution of active load is defined by the speed performance of the prime movers. The distribution of reactive load is depending on the voltage regulation behaviour of the alternators.
8.2.2 Power factor regulation, parallel mains operation Usually, at parallel operation with mains a power factor regulation is activated at the gen-set, so that the alternator voltage is automatically tracked to the mains voltage. AVR systems provided by WKV contain an option on PF regulation. If a PF value is defined at the mains interface location, the current transformers working on the PF regulator have to be located at this interface position. In this case, an exciter current limiter shall be used. Regarding permissible sustained voltage and frequency fluctuation, the EN 60034 rules shall be considered. Other conditions coming from various grid codes shall be discussed based on project.
8.3 Oscillations Periodic power fluctuation is caused by unequal torque characteristics of reciprocating engines. For smoothening of this power fluctuation, the rotors of WKV alternators are generally equipped with a heavy-duty damper cage.
Below mentioned methods for reactive load sharing are usual: 8.2.1 Static voltage droop The terminal voltage of all gen-sets operated in parallel is uniformly reduced depending on reactive current. The dependency of the voltage droop value on the power factor causes a limitation of the reactive power and an equalization of the power factors of the parallel-operated gen-sets. We recommend a droop setting at rated current to: 0 % at PF = 1 1,3 % at PF = 0,9 1,8 % at PF = 0,8 3 % at PF = 0
WKV power plant with 5 gen-sets operated in parallel, producing totally 40 MW of electric power.
Insulation, Alternator Protection
9. Insulation system
10. Alternator protection
WKV alternators are produced according to international rules and regulations. For ensuring the best-possible operating reliability considering various operating conditions, our engineers have, based on long experience in designing alternators, developed and adjusted the insulation system in close cooperation with respectable manufacturers.
10.1 Thermal winding protection All WKV alternators are equipped with 2 x 3 PT100 (RTD) temperature measuring elements for protection of the stator winding against thermal overload. Monitoring or tripping relays shall be provided in the protection panel.
9.1 Composition and manufacture Based on a most-modern impregnation plant, WKV offers Resin Rich impregnation as well as VPI impregnation. All coils used in our alternators are produced in own plants or, in case of increased quantity demand, manufactured and tested by reputable sub-suppliers based on WKV specification. A sophisticated bending of the winding heads / winding overhangs prevents movement or deformation of the coil heads even at extreme loading. The complete insulation system is matching with temperature class “H” for all rotors and for low voltage stators or with temperature class “F” for all medium voltage windings.
10.2 Protection of bearings The bearings of every WKV alternator are equipped with minimum each one PT100 (RTD) element for protection against overheating. Monitoring or tripping relays shall be provided in the protection panel. On special request, vibration probes (SPM nipples) can be used for antifriction bearings.
10.3 Anti-condensation heater For protection against condensate, heating elements are generally used in WKV alternators. The connection voltage is, if nothing else was agreed, 230 V single phase. The rated heater power is depending on the frame size of the alternator. 10.4 Transformers for protection and measuring The terminal boxes of WKV alternators are generally large enough for housing one set of neutral CTs. Mounting of further current and voltage transformers can be realized on request. 10.5 Further protection The application of more protective devices such as vibration sensors, speed measurement etc. can be realized on request.
The in-house hydro power plant operating 2 Francis turbines and producing 320 kW makes the WKV AG to be the first energy-self-sufficient and pollution-free heavy-duty manufacturer in Germany.
F a c t o r y Te s t i n g
11. WKV Test facilities After manufacturing, every WKV alternator is taken to our most-modern test facilities. Detailed tests are performed in order to grant highest reliability of the product. Our customers are provided with a meaningful test report for every single alternator. Below listed tests are forming our standard procedure:
Every first machine of a series
Every further machine
1 Measurement of resistances (cold)
2 No-load characteristic, residual voltage, winding test 2.1 No-load characteristic 2.2 Winding test 2.3 Residual voltage
x x x x
3 Short-circuit characteristic, overload test, SCR, Xd 3.1 Short-circuit characteristic 3.2 Overload test 3.3 Short-circuit ratio SCR 3.4 Evaluation of synchronous reactance Xd
x x x x x x
5 Voltage balance
6 Functional test of AVR-System 6.1 Adjustment of voltage regulator 6.2 Adjustment of under speed protection 6.3 Check of voltage adjustment range 6.4 Adjustment of the parallel operation mode / static droop 6.5 Adjustment of additional modules / features for voltage regulator
x x x x x x
x x x x x x
7 Load characteristic at p.f. = 0,1
8 Over speed / runaway speed test
10 High voltage test
11 Measurement of insulation resistances
12 Determination of efficiency
13 Determination of rated field current
14 Sustained short circuit test
15 Temperature rise test 15.1 Additional temperature rise test for 110 % rated current for 1h
16 Sudden short circuit test
17 Harmonic analysis of voltage waveform
18 Sudden load application at p.f. 0,1, diagram
19 Noise pressure level measurement
20 General check and test of assembled parts, wiring, labels, connection diagram, rating, heater, temperature sensors, etc.
4 Rotating field control
9 Vibration measurement
Picture right: The WKV test facilities in Gutach/Germany with a designed 1200kW drive, most-modern measurement technologies, a comfortable visitorâ€™s area including Internet connection etc. and a highly motivated team of assayers offers optimal conditions for both standard testing and sophisticated FATs.
Worldwide customer support
12. Service to our customers WKV staff would like to support you from the early stages of your project in order to reach technically optimized solutions for the project. Whenever needed your technical staff will receive a through product training associated with the factory test run; also we are geared to extend support for commissioning of your plant. WKV alternators are produced in accordance with internationally proven WKV quality standards.
Picture left: Erection of a WKV alternator in the test field.
Nevertheless, even the best products can fail or might need technical recheck. For this reason, our responsibility does not end after delivering the premium product. WKV are operational worldwide with a network of distribution and sales partners who is standing by for quick and reliable support in case of any technical problems. Wherever we have no representation, we travel immediately. That is our promise.
C u s t o m i z e d S y n c h ro n o u s A l t e r n a t o r s up to 120 t unit weight for Hydro Turbines Wind Energy Systems Gas and Steam Turbines Diesel and Gas Engines Industry and Marine Applications Offshore Applications
Wasserkraft Volk AG Am Stollen 13 79261 Gutach / Germany Tel.: + 49 (0) 76 85 - 91 06 - 0 Fax: + 49 (0) 76 85 - 91 06 - 10 E-Mail: email@example.com Internet: www.wkv-ag.com
You will find our equipment in more than 40 countries all over the world.