When there is a necessity to ensure a continuous energy supply because of a mains failure at our home or at our work place, or to reduce our spending on energy during peaks, then follow our handy guide to choosing the right power generator.

This is not a substitute for a certified electrician, which we always suggest talking to before buying, but it should provide you with enough information to get a solid understanding of some of the key things that are involved.

 What do you need in order to keep working in case of a sudden or programmed grid failure?

Firstly we need to know the starting power and normal running power of all of the items that need to be powered by the generator. All of your items should tell you the nominal running power, however they might not tell you the start-up power required. This depends on the type of mains connection. If it is star or delta, then the start-up power required should be calculated at 3 times the normal running power. If it’s a DOL rating then the start-up power will be equal to 6 times the normal running power of the item. For example in the case of Elevators/Lifts, they may contain a a soft starter of variable frequency drive (VFD) and the starting current can be estimated at 2.5 times the rated current.

In summary as long as we now the kilowatts (kW) of the items we need to keep running in the event of a mains failure, we can then calculate the overall start up power; the final figure being dependent on the type of mains system in use – star, delta or DOL.



Which areas of your installation must have basic lighting?

You need to calculate the total amount of light sources, for that you need to add the consumption of each light expressed in watts (W) then dividing the total by 1.000 to obtain the kilowatts of power consumption from your lighting needs.

By adding the figures from the previous question to the figures obtained for lighting, you will know the approximate power of the generator you need.

Who is in charge of calculating the power needed for the genset?

The decision of the size and power of the genset and its electrical configuration are the responsibility of the electrical, mechanical or engineering department, depending on the kind of project. This department will define:

  • Power needed to cover present and future necessities.
  • The operational requirements to be incorporated in the equipment: manual or automatic start, redundancy with other units or with the mains, soundproofing, auxiliary fuel tanks, heating system etc
  • Legal regulations and local laws (electric, noise, pollution).
  • Selection of the right place to install the genset or gensets (outdoors or indoors, elevation above sea level, dusty environments etc)

Example: How to estimate the power of a generator?

To end this article, we will estimate the power of the genset needed for a 12 floor apartment building, with the following power necessities:

  • 1 elevator with a 15 kW engine: starting with a VFD, 380V.
  • 2 water pumps: 10 HP per unit, star-delta starting (S-T), 380V.
  • 1 Boiler pump: 5 HP, DOL starting, 380V
  • 1 pressurized fire ladder: 15 HP, DOL starting, 380V.
  • Corridors lighting: 5,5 kW (55  100W units), 220V.
  • Entrance hall lighting: 1,5 kW (15 100W units), 220V.
  • Garage door: 0,5 kW, DOL starting, 220V.

Next we design a load table and define the starting power for each item. For this example, we will assume a scenario with the biggest potential demand, one with the elevator and the fire ladder included, although in reality both cannot work at the same time.

Load table
Equipment Rated power (kW) Voltage (V) Equivalent power (kW)  380 V  Start Starting factor Starting power   (kW)
Elevator 15 380 15 VF 2,5 37,5
Water pump 7,5 380 7,5 E-T 3 22,5
Water pump 7,5 380 7,5 E-T 3 22,5
Boiler pump 3,7 380 3,7 DOL 6 22,2
Fire ladder 11,2 380 11,2 E-T 3 33,9
Corridor lighting 5,5 220 1,9 1 1,9
Entrance hall lighting 1,5 220 0,5 1 0,5
Garage door 0,5 220 0,5 DOL 6 3,0
Total with elevator TOTAL 36,6
Total with ladder TOTAL 32,8
Total starting power with elevator (kW) 110,1
Total starting power with ladder (kW) 106,2


We must remember that these figures are an estimate, the definitive power of the genset won’t be bigger than this, but it could be lower. For more exact calculations we must consider other factors as the type of load (lineal or non-lineal), usage factors, simultaneity of start ups, etc.

Worst case scenario is with the elevator working, 110.1 kW, this power is the maximum transient power that could be demanded eventually to the genset, which has a power factor of 0.8 (standard for AC alternators). Now we can calculate the apparent power: kVA=kW/0.8, so the apparent power in our example will be 110.1/0.8= 137.6 kVA, maximum transient power demanded from the genset, based on all the equipment start at the same time. However, the power needed by this equipment when running normally will be 36.6/0.8=45.8 kVA.




Simultaneous start or sequential start?

To define the capacity of the genset we need to consider other factors, like simultaneity and usage factors, applied by the electrical contractors. In our example, we can apply a 0.8 factor to the maximum power calculated, 137.6×0.8=110 kVA, which will be the stand-by power or emergency power that the genset needs to provide. However, if a sequenced start could be programmed, the most critical scenario will be when the elevator starts with all the other equipment running, with this power demand, (36.6 kW – 15 kW) + 37.5 = 59.1 kW. In this scenario, the apparent power will be 59.1/0.8=73.9 kVA. You will notice the difference between both scenarios, 110 kVA vs 73.9 kVA, equivalent to 33% less with the sequential start.

With this information, you are now able to do a preliminary evaluation of your needs of back-up power. To summarize, to choose the right genset you must consider:

  1. Define which equipment/items will be connected to the genset.
  2. Select the power of the genset based on the equipment that will be connected.


Commissioning, the best security protocol for the generator sets

Genesal performs more than 600 commissioning processes every year, of which most are outside of Spain.

Making sure that oil, fuel and coolant levels are optimal, that the air inputs are correct or that the unit has arrived to its destination in the same conditions in which it left the factory, are just some of the technical protocol steps to be performed before the commissioning of any generator set, in a fully comprehensive and absolutely essential check-up coordinated by Genesal Energy’s Guillermo Docampo, thanks to an expertise acquired through 40 years of experience in the energy industry.

Since the founding of Genesal almost 25 years ago, Docampo and the rest of the engineers in the testing team know every unit that is designed and built in the factory inside and out, because their job is precisely that, making sure nothing fails, and making sure that the generator that a client purchases, which is created according to their specific needs, is in perfect conditions before definitively handing it over to the client. “Our service is akin to that of the MOT, we’re the ones that give the go-ahead”, he says.

Commissioning is, therefore, fundamental in order to avoid subsequent issues, to minimize and eliminate risks. While with standard generator sets– like those designed to provide power for a farm or a hotel – the steps prior to a successful start-up are relatively simple, in the case of special generators (nuclear plants, hospitals or combined-cycle plants, amongst other installations) the situation is completely different due to the nature of the unit.

While with standard units it’s quite normal for the After Sales department to assume this task – “a good instruction manual and some basic notions are, in most cases, enough”, the expert states – in the case of special generator sets, the protocol is different: “A Genesal team or a group of technicians that have received training by our staff always travel to the area”, Guillermo Docampo points out.

More than 40 countries

At a global scale, the number of commissioning processes performed by Genesal Energy exceeds 600 a year, which means an average of two a day, although the percentage varies greatly according to the world map. On a national level, 30% of Genesal Energy’s services include commissioning, however this percentage is much higher in the international market, where in countries like Peru they now represent 95%.

In reality, the nature of the generators that are sold outside of Spain (many of them special generators) explain thishigh number of commissioning processes. “It’s always convenient that the start-up and supervision processes are taken out by the manufacturing company because we and our service technicians know the product better than anyone”, says Docampo, who throughout his career has taken Genesal’s energy to more than 40 countries.

Columbia, Ecuador, South Africa, Ghana, Saudi Arabia, Georgia or Qatar are part of thewide client portfolio of the company, where the commissioning service always tends to be included.

Training courses

Without a doubt, training is a basic tool when it comes to commissioning processes, so that the supervision and control tasks that these check-ups require take place with total guarantee.

This way, Genesal provides an average of four courses a year in its headquarters in Bergondo (A Coruña), although its programmes also include training plans and sessions abroad, giving classes to the personnel that will be in contact with the generator set or will be in charge of its maintenance tasks.

“The courses are absolutely necessary in order to have a thorough knowledge of the unit and, therefore, to make sure that everything is okay. We need to guarantee the operation of the generators in times of emergency and in order to achieve this, a good maintenance of the unit is fundamental, which is why adequate training is needed”, Docampo highlights.

Transport & energy – key strategic undertakings for Genesal Energy in Mexico

Two combined cycle power plants – Emplame II in Sonora State, and Valle de Mexico in Acolman – are prime examples of the type of large scale projects which are in Genesal Energy’s agenda for delivery this year in Mexico. The gensets of these two mega-projects by the Mexican Government, have been designed and manufactured almost 10,000 kilometres way in Spain, home of Genesal Energy, a company dedicated to the distributed energy sector, and responsible for exporting the “brand “globally.

GEN2000HC – Empalme II                                   GEN2178TC – Valle México

The numbers tell the true story of Genesal Energy’s international focus and growth: their products can be found in over 30 countries in 5 continents, with exports accounting for 65% of all production. Branches are integrated into Peru, Panama whilst business began in Mexico in 2009 leading to a recognition of the long-term potential of the region, and subsequently a branch office operational since 2014 in central Mexico City. Genesal in Mexico has established a strong presence in the principal business and industrial regions of the capital itself, as well as Monterrey, Leon and Guadalajara, in what is Latin America’s third biggest country.

In the last few years Genesal have been involved in more than 10 major projects and success stories including large scale public works such as the cogeneration power plant in Afranrent, the first submerged transport tunnel in Latin America (Coatzacoalcos) and even the new airport in Mexico City. Today Genesal supplies multinationals, the government and small businesses around the country. “Mexico had to be a leading player in our international expansion. It offers many possibilities.” Explained Iago Crespo, General Manager Mexico for Genesal Energy.


GEN1719HC –  Afranrent Plant                             GEN2407H – Tunnel Coatzacoalcos

The company, whose growth continues unabated in this central American region, and that has doubled their turnover in 3 years, is now setting its sights on the energy and transport industries, sectors with enormous potential for business, especially with the commencement of the energy reforms carried out by the government.

“In the past, resources were in the hands of state-controlled companies, but procedures have changed, there is less bureaucracy, and more options,” explains Crespo, who confirms that the Mexican client is demanding in terms of timings and prices “and above all in the service expected.”

Innovation and on-demand service

Without doubt, one of the secrets of Genesal Energy’s success in the international market has been their ability to quickly adapt. Through their constant innovation, and high-level engineering, a very personalised service can also be noted, added value in Mexico which does not go unnoticed. “The difference is in our comprehensive service, quality and flexibility.” points out Crespo, “When we turn up we focus on supply, installation and maintenance, but more and more our clients insist we act more comprehensively, offering for example complete genset packages.”

Genesal Energy Technical Support Services grows 40% in genset maintenance in just 1 year.

Here at GENESAL ENERGY we believe that customer service does not stop when we close the sale of a product, on the contrary, it is when the sale has been made that the real work begins in terms of building customer loyalty. And that is done through efficiency, quality and building trust. Putting together and designing a maintenance program based on the individual clients needs whether for large fleets or individual genset units, is the hallmark of our Technical Support Services (SAT in Spanish). In the last few years our growth in this business unit has been spectacular, in many ways an occurrence brought on by clients who continuously demand more and better from Tech Support.


GENESAL ENERGY Tech Support (SAT), activities are based around maintenance, installation and the repair of generating sets, offering a very specialised level of attention by highly qualified professionals. Our objective is to ensure your product has the longest most efficient life span possible.

“Those who choose to invest our maintenance services are basing their choice on reliability, but also in trust, and peace of mind” assures Marga Gonzalez, director of GENESAL ENERGY Technical Support Services. She goes on to say that 40% growth in maintenance services for gensets in just 1 year clearly demonstrates an evolutionary market. Customer are more demanding than ever, and GENESAL ENERGY has taken up the gauntlet.

Our after sales support, is made up of almost 30 professionals, and is most definitely added value for the company, a part of our operation which carefully adapts to the supply/demand factors of the market offering solutions, services and adapted products, or in one word personalised. The GENESAL ENERGY Technical Support Service offers a wide range of solutions including three key areas of maintenance – corrective, preventative and predictive.

  • Corrective Maintenance – Solutions for breakdowns which depending on their origin (mechanical, electrical or electronical) cause operational malfunctions, which can even leave a genset out of service, which can potentially be a grave situation for the end user.
  • Preventative Maintenance – These services are adapted to the type of operation the genset is destined for, either PRP or ESP. The maintenance is adapted to the amount of usage given to the genset and may consist of annual technical inspections, supervision and virtual control amongst others. It also includes updating maintenance and improvements. In these cases, gensets are adapted to the changing circumstances in the customer’s needs (new alarms, config changes, control panel changes etc).
  • Predictive Maintenance: This entails personalised support over the phone and remote management, meaning Genesal Energy is your global reference at home and abroad when it comes to detecting potential breakdowns or faults in gensets worldwide using fixed or mobile wifi connections. Also as any necessary changes to the genset are carried out by remote management systems, the time spent on preventative maintenance is considerably shortened.

24/7 Support

Remote Control Systems fall in to the category of things that differentiates GENESAL ENERGY, and so does our ability to respond to our clients 24/7 throughout the entire year, offering non-stop high quality technical assistance.

Additionally, our dedication to R&D through our sector unique Technological Centre for Distributed Energy (CETED in Spanish), has not only consolidated our position as a market leader in our field, but its ongoing work compels us to be better with each project we do, to be better in every department and also in every new line of business.

In-House Technical Services

It is by being different that our Technical Support Services (SAT), can offer the highest levels of service: personalised solutions, our own high-powered load banks (unique in Spain), and of course a team of first class technical experts.

“In Genesal we have our own in house technical support services, something which distinguishes us from other companies in the sector”, indicated Marga, who also highlights the importance of being able to count on in-house experts who can intervene in any incident. She also went on to say, “Our team always have the support of the main factory, meaning our clients are covered at all times, something which is fundamental for us to offer the best service possible.”

The possibility to channel the incident, emit a diagnosis and repair the incident from Genesal Energy in record time without using external assistance is yet more added value from our after sales service. Why? Because it transmits reliability and trust, an essential value when discussing emergency generator sets where the solution process must be reliable and safe, but also quick.

Turnkey solutions are another service intimately connected to the efficiency offered by Technical Support Services. “We undertake the entire commissioning process of generators. From start to finish, full circle.” Marga tells us, who goes on to say that they have a specialist mobile team that can travel to the gensets on-site location to study and evaluate the distinct possibilities of an installation.

With the aim of guaranteeing a quick and immediate response anywhere in the country, GENESAL can also count on approx. 10 official technical services spread around Spain, covering the entire territory. “They are all highly capable professionals, who understand all the products leaving our factory to perfection.” The director reminds us.

Ongoing Training

One of the pillars of the Technical Support Services division, as with other departments in the company, is continuous training. The majority of this takes place in GENESAL’s very own inhouse training centre, allowing our own technicians and our external official support services to participate in all manners of professional development.

Knowledge and constant innovation are without doubt the correct path to follow to offer our clients the best and most impeccable attention possible combined with the best services.