Power You Can Trust


As the industry comes together at the Institute of Healthcare, Estates, Energy & Management Conference, WB Power Services (WBPS) has announced a further £2 million investment in Stage V generator compliance, on top of the £4 million it has already committed.

The reason for the investment is in response to the EU seeking to improve air quality and introducing increasingly stringent emission standards in the form of Stage V regulations for certain types of non-road mobile machinery, which includes diesel generators. The new standard became effective from 2019 for engines below 56 kW and above 130 kW, and from 2020 for engines between 56 and 130 kW.

The scope of regulated engines was also widened to include compression ignition (CI) engines below 19 kW, and above 560 kW, spark-ignited (SI) engines above 19 kW, and other previously unregulated engines. This includes Category NRG – generator set engines above 560 kW.

The standards have meant the addition of new systems such as particulate filters and other associated equipment to limit the release of harmful particles into the atmosphere which WBPS has been implementing over the last few months, with the project due to complete in 2023.

As the leading critical power provider, WBPS will have invested £6 million by the end of Q4 2022 for rental and industrial generators, ranging from 20-330kVA.

The table shows a summary of the Stage V emission standards over the various engine power ranges, from 0 kW through to 560 kW and any higher power rating:


Kohler is the leading provider of engines, generators and UPS products and WBPS is extending its authorised distributer partner status by investing in its emission reduction technologies. As a supplier of turnkey critical power infrastructure, from single generators (10kVA to 4.5MVA+), to large multi-synchronous packages, WBPS has built up a large fleet of over 1000 ‘Rental Compact’ Kohler generators, allowing customers to hire the exact units wanted, for the time needed.


Stage V regulation means that to be compliant, engines must have an after-treatment system to provide the required filtering efficacy. Kohler has achieved this by integrating different systems to reduce microparticles and nitrogen oxide. The stages include:

  • Having a Common Rail injection system with optimized computer calibration to minimize pollutant production
  • Incorporating an EGR valve (Exhaust Gas Recirculation) to manage the quantity of exhaust gas, re-injecting a part of it, which is then cooled via a heat exchanger, into the engine intake to be burned (limiting NOx production)
  • A DOC (Diesel Oxidation Catalyst) has a honeycomb structure covered with catalyst metals helping some of the carbon monoxide gases, hydrocarbons and nitrogen oxides transform into water, carbon dioxide and nitrogen dioxide, therefore being reduced to the mandatory limit values.
  • The final post-treatment system sees the remaining particles pass through a DPF (Diesel Particle Filter), which collects and burns them using heat from the engine and DOC

Kohler’s technology minimizes the number of operator interventions and includes using a ballast to space DPF regenerations and avoids the need for forced regeneration in maintenance.

Kohler has made significant investments into research and development to produce a range of Stage V engines across all power ratings, with four new generators being launched onto the market by the end of the year. The Stage V products are the least-polluting engines available within their target utility and construction applications and include products for both the rental and industrial markets.

Comments WBPS Managing Director, Andy Wilmott: “We have been working with our customers since the new regulations were announced to support them with any changes that were needed to be Stage V compliant. This has included sharing technical data written into specifications and providing the most suitable optimised products, spanning healthcare, datacentres, utility companies and telecoms. We are focused on completing the rollout with the additional £2 million investment which will be complete by the end of 2023.”

WBPS can directly supply Kohler products to the rental market supporting five core requirements. These are:

  • Robustness: performance is guaranteed thanks to the Kohler impact-resistant design which includes 24-hour autonomy fuel tank and heavy duty air filter with restriction indicator
  • Handling: features to ensure easy handling during transportation include an integrated lifting eye, forklift pockets, frame protection pads and a traction bar. However, the new Stage V generators are some of the most compact on the market
  • Safety: Both service life has been improved thanks to new protection features and there are enhanced safety features during their handling, connection and operating phases
  • Usability: Connection and operating phases are more comfortable for users and have dedicated access to controller and power connections
  • Maintenance: Structured design allows quick and easy access to consumable and mechanical parts during cleaning and maintenance. The generator sets performance is facilitated by the Kohler APM403 controller which displays data related to post treatment