|Welcome to our page…the company exists to support the work of Kisiizi Hospital and to extend the benefits of electricity to the wider community. KHPL is a company incorporated in Uganda, limited by guarantee and trades under the name Kisiizi Electricity.
Its objectives are:
- to supply electricity 24/7 to the clinical areas of the hospital
- to raise revenue by the sale of electricity
- to supplement the hospital’s finances by remitting to the hospital any surplus after expenses
We are proud of our installation and in this website, we want to make known the details, both operational and technical, in case they are of interest to others. Please feel free to contact the company by email if you want further information.
Contents of our page:
- Latest news
- Company details and personnel
- Generating operations
- Electrical distribution arrangements
- Electricity sales
- Overview of system performance
- Annual reports
- Hydro history at Kisiizi
- External links
1. Latest news
Posted 15th January 2023
With the two turbines now having 39 and 13 years of operation, the challenge of maintenance and repair is a constant for the KHPL team.
This month the Polarr relay started to malfunction; it controls the supply to the 11 kV distribution lines; fortunately a spare had been brought out in October 2022 but it was a spare which had been purchased on eBay and there were doubts about whether it would work; it was installed and thankfully worked as it should.
The cost of spare parts is a difficulty for enterprises like Kisiizi Electricity, and as in this case, parts are tracked down, where possible, at less than the manufacturer’s price, and couriered to the hospital by people visiting from UK so that freight and import costs are minimised.
Hand over of the eBay Polarr relay in Oct 2022
2. Company details and personnel
Official correspondence to:
Kisiizi Hospital Power Limited, PO Box 109, Kabale, UGANDA.
Email address: email@example.com
Mobile phone: +256(0)782583145
The Bishop of North Kigezi Diocese, Church of Uganda
The Medical Superintendent, Kisiizi Hospital
The Administrator, Kisiizi Hospital
Absa Bank (formerly Barclays), Kabale
1 x Diploma Electrical Engineers / Qualified Installers
3 x Electricians
3. Generating operations
The company operates two hydro-electric sets and one stand-by diesel set. The water turbines make use of a geological fault which has created a 36m high waterfall in the river Rushoma.
The river flow varies with the seasons. The smaller turbine’s lower water requirement means it can run at full power in all seasons whilst the larger turbine has to run at reduced flow in the drier months.
The three generating sets are only capable of running independently of each other. There is no provision to synchronise their outputs but the larger turbine made by Ossberger is equipped to synchronise with the Uganda national grid in the future.
A sluice gate close to the top of the waterfall controls the flow of water into an 80m long channel which carries water to the two penstocks.
Drone view looking down on waterfall from above
For the water supplying the Ossberger turbine, this channel widens to create a desilting chamber. An arrangement of sluice gates permits different combinations of turbine operation to be achieved. The silt in the de-silting chamber needs to be mobilised and flushed out via a bypass channel every month.
Trash racks protect the openings from the channel into the penstocks and these are cleaned by a maintenance worker using a rake, twice a day.
After a catastrophic flood in 2010, when exceptionally high river levels caused overspilling of the channel walls and a mudslide down to the turbine house, the walls of the channel were raised and deliberate overflow points created to channel water in a way that would not cause a repeat mudslide. These additional measures can be seen in the above picture.
For the technically minded:
MAIN GENERATOR – Commissioned in 2009
Manufacturer : Ossberger (Germany)
Turbine type: Crossflow
Maximum power: 294 kW
Net Head = 38.6m
Flow = 1.0 m³ / s
8 mm thick steel + bolted compression sleeve couplings
Turbine speed = 500 rpm
Thomson and Howe 202kW electronic
load governor with turbine water
EME 415 v 50 Hz 400 kva 1000 rpm
Gear box: Flender, oil cooled, Step up 1: 2
Protection and grid synchronisation: Cegelec
SUPPLEMENTARY HOSPITAL GENERATOR – (Main Generator from 1984 until 2009)
Manufacturer: Gilkes (UK)
Turbine type: Turgo
Maximum power: 60 kW
Net Head = 29.8 m
Flow = 0.26 m³ / s
Penstock: Welded steel
Diameter: 355 mm
Length: 73 m
Speed = 564 rpm
Headley electronic load governor
Drive: Poly V belt, Step up 1: 2.67
Alternator: Meccalte 415 v 50 Hz
90 kva 1500 rpm
DIESEL STANDBY GENERATOR
Model: Broadcrown BCJD100P (UK)
Maximum Output: 80 kva
Engine: John Deere 4045HF
Fuel cons: 23.1 litres / hr at full load
4. Electrical distribution
Power is distributed by a ‘mini-grid’ which extends 8 km towards Nyarushanje and 2 km to Upper Kisiizi. There is a 315 kva step up transformer at the turbine house which takes the voltage to 11,000 volts. Power then passes through an auto-recloser which disconnects the 11kv lines in the event of a fault on them.
Power to the hospital, which is situated close to the turbine house, is distributed at 415 v by underground cable. Connections are so arranged that the Gilkes and diesel sets are only capable of supplying the hospital whilst the Ossberger can supply the entire grid.
Eight 50 kvA and two 25 kva transformers step the voltage down for local distribution to customers.
5. Electricity sales
Use is made of a pre-payment system provided by the South African company Conlog. The office vending operation uses Conlog’s Ultima software to print a 20 digit code on a slip of paper which is handed to the customer in exchange for cash. The system is very like buying air-time for a mobile phone.
The customer enters the code to the User Interface Unit (UIU) in his premises and the meter will then display the number of kilowatt hours that he has paid for. To discourage tampering with the meters they are normally located at the top of the pole bringing power to the premises, whilst the UIU is within the home. Most customers have single phase Bec 41 Conlog meters but some small businesses, such as woodworkshops, grinding mills and battery charging outlets, have Bec 33 three phase meters.
6. Overview of how the system works
The Ossberger turbine is the mainstay of power generation. The Gilkes acts as a back-up but has only enough output to supply the hospital. The diesel provides further back-up to the hospital if both water turbines are down.
In the drier months, the available water is insufficient to power the Ossberger at its full rated output. This situation is managed by limiting the opening of the vane that controls water flow to the turbine rotor so that it will not allow more water to be taken than is available. The characteristics of a crossflow are such that it still performs with high efficiency, 83%, even when operated with flows down to 40% of its design maximum flow.
Trash carried in the water is a problem. Mostly this is vegetable matter thrown into the river from the fields in the valley upstream, but plastics are common and even dead dogs have been known. A single screen at the entry to each penstock strains everything out and a maintenance worker is employed to clean the screens twice a day.
There is a heavy silt burden in the water, especially in the rainy months. It is encouraged to sediment out by slowing down the water flow in a desilting section of the headrace channel. The silt is then washed through via a bypass sluice and that is done every month.
The customer base is aproximately 400 metered supplies, some of them hospital staff and some general public. Demand for power during each day has clear peaks and troughs. In the dry months, customer demand at peak times can exceed generating capacity resulting in blackouts. The hospital supply is however on a separate line so power can be maintained there even though it may be lost to others.
The Uganda National Grid has extended its distribution system into the area of the Kisiizi mini-grid during 2011 and there is the possibility of linking to it in the future.
Maintenance of the generating plant and distribution system is done by the Electrical Engineers and Electricians employed by Kisiizi Electricity. The Engineers and Electricians have been trained further as part of a collaboration with the UK company Scottish and Southern Electricity (SSE) . They are able to trouble shoot faults in the generators and make good damage to the distribution system. They are also the ones who connect up new customers.
The 11 kv grid is carried on treated wooden poles. The area supplied is broken into eight areas each supplied at 415 / 240 volts by a 50 kva step-down transformer. Two 11 kv line switches near the turbine house control power into the two main outgoing lines, one to Upper Kisiizi and the other to Nyarushanje. There are a further two line switches on the Nyarushanje line.
A GVR (Gas filled Vacuum auto-Recloser) and Polarr Relay (both made by Hawker Siddeley Switchgear, UK.) monitor the power feed to both lines and if there is an overload or earth connection, the power is automatically disconnected. The equipment then enters a pre-programmable sequence of automatic reconnection which detects whether the fault is transient or ongoing, leading either to reconnection or permanent disconnection respectively.
7. Annual reports and accounts
8. Hydro history at Kisiizi
- view an 18 min film showing the history of hydro power developments here
10. External links: