How many times did your Dad tell you ‘always use the right tool for the job’. It’s an old adage, but it applies equally to recommendations for emergency lighting UPS power supplies that we make to our customers.
As one of the leading suppliers of UPS systems in the UK & Ireland, KOHLER Uninterruptible Power Ltd (KUP) are often asked about using our uninterruptible power supplies range for centralised emergency lighting applications. They can, but not without considerable oversizing. Our recommendation is to use our KOHLER EL range of static inverter emergency lighting systems for this application – ‘..the right tool for the job’.
The KUP KOHLER EL range covers both single-phase static inverter and three-phase static inverter emergency lighting systems with applications and lighting load requirements from 500VA to 160kVA. Passive Standby, Active Standby and No-Break operating modes are also supported, but what’s the difference?
Static Inverter Operating Modes
With a Passive Standby static inverter emergency lighting system, the lighting load is normally powered directly from the mains supply, but in the event of a power outage, it automatically transfers the load to the emergency lighting inverter. A UPS battery provides power to the emergency lighting inverter to support the lighting load. As the uninterruptible power supplies are sitting in idle until required, effectively on demand, there is an energy saving benefit. Additionally, the UPS system components are less stressed, so extending their working life and need less maintenance. Passive Standby static inverter emergency lighting systems are ideal for use with fluorescent and incandescent lighting.
As the name suggests, a No-Break static inverter emergency lighting system is always on, with the lighting load continuously supplied by the static inverter. This guarantees there is no changeover switching of the power supply to the load when the mains fails and makes them ideal for maintaining high-pressure discharge lights as well as fluorescent and incandescent emergency lighting. Further, the lighting load is unaffected by any variations in the mains power supply and is constantly supplied with stabilised, smoothed and conditioned power, so the lights don’t flicker and lamp life is extended.
A subtle difference with an Active Standby static inverter emergency lighting system is that although the static inverter is constantly running, it is off-load. This design reduces stress on the static inverter, subsequently reducing the risk of UPS system failure at the critical time the static inverter takes the lighting load at mains failure.
Safety Regulations for Lighting UPS
‘Safety first’, another old adage, is of paramount importance with emergency lighting UPS power supplies, after all their prime function is for life-saving. As you would expect they are highly regulated and have to be compliant with the European Norm EN50171 Standard. All KOHLER Uninterruptible Power’s KOHLER EL static inverter emergency lighting systems comply.
Another critical area of compliance required by the EN50171 standard is for static inverters to support a continuous overload if there is a circuit disruption within the emergency lighting UPS power systems. The KOHLER EL static inverter range all have a high overload capacity and are able to support continuous overloads of 120% of the nominal power rating.
Static Inverter Service and Maintenance
Equally important to choosing a static inverter is making sure it is supported over its life by regular service and maintenance. A well maintained static inverter will ensure the integrity and availability of the emergency lighting UPS power supplies when it is needed and is essential for both safety and peace of mind. This philosophy applies equally to uninterruptible power supply batteries, which are at the heart of any centralised emergency lighting UPS system.
UPS battery duration is deemed by the specific requirements for all emergency lighting UPS installations, but a long autonomy of three hours is typical. That means a significant amount of UPS batteries and it is essential a robust UPS battery care regime is used to ensure they provide a reliable uninterruptible power supply when a mains failure occurs.
On top of regular & periodic UPS battery service, KOHLER Uninterruptible Power is seeing a trend towards the adoption of our PowerNSURE dedicated UPS battery monitoring, management and care system within the centralised emergency lighting UPS power systems we supply. PowerNSURE monitors the condition of every UPS battery individually and regulates the UPS battery charging process to avoid under-charging, guaranteeing the availability of UPS batteries at all times.
So a number of key considerations with respect to static inverters and UPS batteries for centralised emergency lighting UPS systems. It is all about ‘…choosing the right tools – product & service – for the job’.
For more information regarding any of our uninterruptible power supplies, products, or services, you can get in touch with KOHLER Uninterruptible Power via our contact page or call us on 0800 731 3269.
