Inverters - what you need to know
What is an inverter?
An inverter converts AC or alternating current to DC or direct current. AC power is typically the primary power source because it is more stable and better travels distances without power loss over DC power.
In typical power situations, inverters store energy in their battery banks as DC power. When power is lost, inverter circuitry converts the DC power in the batteries back to AC power to operate lighting fixtures, exit lights, or other non-lighting items like ventilation systems until power is restored. For more information, click here.
Why use an inverter over integral emergency battery packs?
One significant advantage to using an inverter over an integral emergency battery pack is the inverter allows the light fixture to operate at full lumen output during an emergency or power outage. This means the emergency lighting system can use fewer fixtures to help occupants evacuate safely.
A second advantage is an inverter system can save on project installation and maintenance costs. Many considerations should be made when determining whether your project should use an inverter. For example, how many fixtures will be used as part of the emergency lighting system? Are there exit signs? What are the estimated labor costs for installation? How much will it cost to maintain the emergency lighting?
Typically, one should consider inverters if 5-7 emergency units or lighting fixtures will be required to meet minimum lighting levels in an emergency on the project. Inverters can reduce maintenance costs because it takes less time to test at the inverter versus walking to every lighting fixture for your monthly 30-second and yearly 90-minute tests. In addition, most inverters are self-diagnostic, and some units can record the testing documentation automatically for the maintenance department. This saves time and money and keeps the building in compliance.
Inverter Sizing and Install
Lighting inverters range in size, wattage, and installation locations. The smallest inverters, often known as micro-inverters, offer as little as 20w of power and are smaller than a ceiling tile. They can be mounted recessed or surface mounted in the ceiling or wall. The largest inverters can offer 18,000 watts of power or more and must be stored in well-ventilated utility closets because the cabinets that house the batteries and circuitry can be as tall as six feet. The specific project requirements determine the size and location of the inverter needed.
Inverter Maintenance – it’s simple.
Visually inspect the batteries and cabinet and remove any dust or debris. Keep items away from the top and sides of an inverter so nothing prevents airflow from around and within the unit.
In summary, inverters offer several advantages over integral emergency battery packs. They could be less money to install and maintain. They can make it easier for the maintenance staff to keep documentation of their monthly and yearly testing. Determining whether or not one should use inverters can take a little upfront time, but the payoff could be in spades over the project’s life.