During the past week, our electrical team has tested and examined the current electrical systems at both Nyiragasigo and Kigogo sites. We obtained useful information in terms of the following three aspects of the system. The first aspect is the design, layout, and subsequent modifications of the electrical set up. The second aspect is the knowledge and usage habits of the site operators. Observations of human interactions with the system help guide our future design. The third is the kiosk architecture, which determines how the space can be used.
As expected, the current electrical system has a number of problems. Some of these issues were due to the original DHE design, while others resulted from modifications to the system by local technicians. The site operators have not noticed any issues with the current system, as it works well for normal operation. Our updates aim to protect the system against the most extreme of fault scenarios.
Firstly, the wires in the current system are too skinny. If high current levels pass through the wires, they can potentially heat up as current passes through them and dissipate valuable energy as heat. The thicker wires that we are using in the new system will dissipate less heat and waste less energy. This modification raises the overall efficiency of the system.
Moreover, all of the circuit breakers that were implemented in previous trips have mysterious disappeared from the Nyiragasigo system, and the Kigogo system has been left with only two 40A breakers. Circuit breakers turn off and break the circuit when they detect that a current above their rating tries to pass through them. The absence of circuit breakers is dangerous because circuit breakers protect wires, expensive equipment, and people from large currents. Missing circuit breakers mean missing safeguards against accidents.
In addition, some of the current connections have been made using either two touching wires, held together by the electrical tape wrapped around it or by exposed terminals that could be shorted.
Other issues with the current system are the absence of a permanent storage battery and the disconnection of dump load resistors from the system. The permanent storage battery prevents the voltage from fluctuating by absorbing and releasing extra charge when necessary. Dump load resistors dissipate extra energy from the system when the batteries have been fully charged. Without these two, the system loses its ability to regulate voltage. As a result, the current system has a much higher probability of experiencing uncontrollable voltage spikes.
The storage batteries were sold to users as personal batteries to profit the site. I asked the site operator why the dump load resisters were disconnected. He said that the dump loads were heating up during battery charging and “taking power away” from the batteries. They believed that without the dump load, batteries would be charged more quickly and fully. However, charging batteries is analogous to feeding hungry people. When someone is already full, the extra food that they can no longer consume has to be “dumped” somewhere. If the extra food is not dumped but is fed to the person instead, the man will suffer. Overcharging batteries is unhealthy for the batteries and can shorten their lifespan.
Another issue is how disconnected battery connectors and clamps are used in the system. When removing a fully charged battery, the site operator takes off both clamps to the battery and reclamps the positive end to a plastic box while allowing the negative clamp to dangle freely in the air. This is dangerous, as any contact between any of the system’s positive and negative clamps will short the system and induce a large current through the system.
The 13X electrical team has put many careful considerations into the system. We used sturdy screw-in wire connectors, thick wires, and enclosed intersystem bonding terminals to minimize possible tampering of the circuit. We also design shelves with insulated storage places for battery clamps. Sophie, Shinri, and I have worked to take into consideration the site operators’ habits.
We have already assembled the electrical systems for both of our sites and are waiting on the completion of the civil modifications to the two sites before implementing our updated electrical systems. Testing of our new system has been going well. Yesterday, we spent five hours at Nyiragasigo taking current and voltage measurements for all of our components and have already proved that the new system has a higher power output than the one we will be replacing.
Every day, when we walk out of the kiosks at our two sites, we are greeted by layers beyond layers of different shades of green. We see the banana trees line the path to Nyiragasigo and the butterflies that flock by the stream next to the Kigogo kiosk. Banda village and its kiosks are already a part of us, and we hope that our efforts will help the hydro systems be the best that they can.