Journal Technical and Vocational Education Science

Wind turbines are typically classified as Horizontal Axis Wind Turbines (HAWT) or Vertical Axis Wind Turbines (VAWT). VAWT has a superior ability to accelerate from rest to rotation than HAWT, allowing it to rotate the rotor even when the wind speed is low; additionally, the produced torque is relatively high. Using the Savonius helix VAWT is one of the numerous methods for enhancing VAWT performance. The effect of the number of blades and the blade twist of the rotor or the angle of rotation of the blades on the rotor from the bottom end to the top end on the speed cut generated by the VAWT Savonius helix was investigated experimentally. Variations in the number of blades used in the study included 2 and 3 blades, as well as 90°, 180°, 270°, and 360° for the rotor twist blades. In a wind tunnel, data was collected at wind speeds ranging from 0 to 5 m/s. The best performance research results were obtained With three blades, a twist angle of 180 degrees, and a cutting speed of 1.51 m/s. By modifying the Savonius Helix VAWT design in this study, it is possible to increase the efficiency and performance of turbines, mainly when used at low wind speeds, and the potential for using wind energy as a more efficient and sustainable alternative energy source.

With the increasing development of technology, which uses electricity as its primary power on DOI: https://doi.org/ 10.20961/jiptek.v16i2.71389 average, the need for electricity is increasing (Suharyani et al., 2019). The final national electricity demand for 2019-2050 in the Business as Usual ( BaU ), Sustainable Development (PB), and Low Carbon (RK) sectors will increase with an average annual growth rate of (5.0%) each, ( 4.7%) and (4.3%) where the status of electric car and electric motorbike users currently reaches 229 units and 1,947 units with a production target in 2025 to reach 400,000 units of electric cars and 1.7 million units of electric motorbikes (Arinaldo et al., 2021).
Energy use in Indonesia is still dominated by non-renewable energy derived from fossils, especially oil and coal (Azhar & Satriawan, 2018 The availability of fossil energy has recently decreased, so the price tends to rise (Tirono, 2012). This can be dangerous for the security of the Indonesian people's electrical energy, which is increasingly depleting; for this reason, renewable energy is needed. Renewable energy is energy that comes from renewable energy sources. Renewable energy sources are energy sources that can be used indefinitely and will never run out because they can be restored in a relatively short time (Azhar & Satriawan, 2018). Renewable energy sources include hydro, solar, wind, geothermal, biogas, biomass, and ocean waves.
Wind energy is a promising renewable energy source because of its availability (Abdelaziz et al., 2021). Several countries are currently considering wind energy as an essential source of energy. Moreover, developing countries have realized in the last decade the importance of wind energy (Mohamed et al., 2021). This energy can be used for power generation using the Wind Energy Conversion System (SKEA). Wind turbines can convert wind kinetic energy into electrical energy through generators (Wibowo, 2018).
However, using wind energy in Indonesia has yet to receive special attention (Cendrawati et al., 2015). Setting up a wind power plant is more accessible than other plants.
Generally, wind turbines are divided into two types: Horizontal Axis Wind Turbines (HAWT) and Vertical axis Wind Turbines (VAWT). VAWT has the ability of the turbine to accelerate from rest until it can rotate better than DOI: https://doi.org/ 10.20961/jiptek.v16i2.71389 HAWT so that it is able to rotate the rotor even though the wind speed is low; besides that, the torque produced is relatively high (Alit et al., 2016). VAWT does not require an orientation system according to the wind direction. The VAWT is also very suitable for operating in the city centre due to its good response even to fast changes in wind direction. One of the most widely used VAWTs is the Savonius turbine (Kothe et al., 2020). The Savonius turbine is considered one of the best VAWTs for converting kinetic energy from the wind into mechanical energy at low wind speeds (Abdelaziz et al., 2021). The main disadvantage of the conventional Savonius VAWT is that it generates a negative torque at a particular blade rotation in the range between 135° and 165° and between 315° and 345° with significant torque variations (Kamoji et al., 2011). On the other hand, the helical Savonius VAWT produces a positive static torque coefficient in all blade rotors with better performance (Seralathan et al., 2022).
This type of wind turbine has a low rotational speed with high torque (Latif, 2013).
In the Savonius helical VAWT study in India, the optimal wind turbine obtained the highest torque at a wind speed of 5.12 m/s (Micha Premkumar et al., 2018). This is evidenced that the Indonesian region has an average speed ranging from 3 m/s to 5 m/s (Ismail & Saleh, 2015). However, research conducted by (Azirudin, 2019) found that at the height of 30 meters at certain times, it reaches 4.50 m/s, while at other times, the wind speed is only 1.19 m/s, for it is necessary to design wind turbines that are suitable for low wind speed areas and can meet electricity needs (Sumiati & Amri, 2014). At very low wind speeds, it is most likely to optimize the Savonius helix VAWT in Indonesia. In another study, comparing one and two levels increased the strength coefficient of the two-stage Savonius helix VAWT by about 7.69% (Seralathan et al., 2022). Saha et al. (2008) investigated the helical VAWT Savonius turbine by combining the variables of semicircular and rotating shapes, number of blades and use of valves. The test speed was varied between 6 to 11 m/s, and it was found that the optimal number of blades was two for one, two or three levels. The two-stage rotor has a higher power coefficient. In another study, the VAWT Savonius helix used a 180° twist rotor, stating that its overlaps ratio 0 .242 is better than an overlap ratio of 0 or no overlap (Damak et al., 2018    As depicted in Figure 3, the rotation speed sensor uses a disk encoder sensor that works almost the same way as an IR sensor was an DOI: https://doi.org/ 10.20961/jiptek.v16i2.71389 infrared light sensor used to detect obstacles or objects to detect obstructions or objects (Arfandi & Supit, 2019). The difference is the disk encoder sensor. This needs a plate with several symmetrical holes on the sides outside. These sensors will read How many sensors go through the hole in one seconds later _ converted to rpm.      (Gupta & Haldar, 2017).

This
Quantitative data obtained was processed in tabular form. The data was shown graphically to help with information delivery and was then contrasted and examined. DOI: https://doi.org/ 10.20961/jiptek.v16i2.71389

RESULTS AND DISCUSSION
The results and discussion in study related influenced the amount of blades and blade rotor twist against a speed cut VAWT Savonius helix.
Cut in speed is the minimum speed wind requires a turbine to spin and earn Power electricity (Sulaksono, 2019). The results of the cut in speed measurement data obtained can be seen in form According to the data, the correlation of blades and blade twist rotor as follows:

Conclusion
Based on the results and discussion