Power for LED displays in Nepal: voltage swings, UPS and generators

Why does power matter so much for LED displays in Nepal?

Power matters because voltage swings, surges and sudden interruptions damage LED power supplies and receiving cards, and they cause screens to drop out mid-content. Nepal’s supply has improved greatly, but many sites still see fluctuating voltage, brief cuts, changeovers between grid and generator, and lightning-induced surges during the monsoon.

An LED screen is a large electronic load with dozens or hundreds of switching power supplies. Each tolerates a range of input voltage, but repeated over- and under-voltage, spikes on changeover and poor earthing shorten their life. When power supplies fail, they often take receiving cards or modules with them.

The good news is that well-designed power protection is not complicated. It is a question of doing the basics properly: a dedicated circuit, protection, surge suppression, earthing and the right backup for the right parts.

What electrical supply should an LED display have?

An LED display should have its own dedicated supply from the distribution board, sized for the screen’s peak power draw with headroom, with appropriate circuit breakers, residual-current protection and surge protection. Sharing a circuit with air-conditioning, lifts or kitchen equipment invites trouble.

Peak power and average power are different numbers. Peak is the draw at full brightness on a full-white image; average is typically far lower in normal use. Cables and breakers must be sized for peak, while running costs depend on average. Large screens are usually split across several circuits, and three-phase supplies are balanced across the phases.

Earthing deserves its own mention. A good earth protects people, protects the electronics from surges and reduces interference on data lines. Outdoor screens and metal structures need a properly tested earth, not a connection to whatever pipe is nearby.

Does an LED display need a voltage stabiliser?

An LED display needs a stabiliser where the local voltage regularly moves outside the range the power supplies tolerate — common in parts of Nepal, at the end of long rural lines and in buildings with heavy shared loads. Where the supply is stable, good surge protection and a dedicated circuit are usually enough.

The survey checks this. Measuring voltage at the site over different times of day shows whether it dips during the evening peak or rises at night. If it does, a correctly rated automatic voltage regulator protects the screen from sustained over- and under-voltage. It should be sized for the screen’s peak load with margin, and it should not itself become a single point of failure without a bypass.

Surge protection is needed everywhere, stabiliser or not. Surge protective devices at the distribution board — and on data lines for outdoor screens — absorb the spikes from lightning and switching that stabilisers cannot react fast enough to stop.

Which parts of an LED display should be on a UPS?

In most installations the control system belongs on a UPS: the sending card or controller, the media player or computer, the video processor and the network equipment. Keeping these running means a brief cut or generator changeover does not reboot the system, lose the schedule or corrupt content.

Putting a whole LED screen on a UPS is possible for small indoor screens, and sometimes justified for control rooms and critical information displays that must stay on. For large outdoor screens it is rarely practical, because the UPS would need to be very large to carry the screen’s peak load. In those cases the screen rides through cuts on generator, and the UPS keeps the control system alive until the generator takes over.

Choose an online (double-conversion) UPS for control equipment where the supply is poor, because it isolates the load from the mains completely. Check the batteries regularly; a UPS with tired batteries gives a false sense of security.

How should a generator be sized for an LED screen?

A generator for an LED screen should be sized for the screen’s peak draw plus the other loads it carries, with comfortable headroom, and it should hold a stable voltage and frequency. An undersized or unstable generator causes flicker, resets and power-supply stress.

Switching power supplies draw a surge of current when they start, so a large screen powering up all at once can overload a generator that runs it happily once warmed up. Staggered start-up solves this. The changeover from grid to generator should be automatic and clean, and the LED screen should not be the first load to hit the generator after it starts.

For events, keep the screen on its own generator or its own distribution, away from sound and lighting loads, and confirm the generator is properly earthed. Plan fuel for the full event and a margin.

How do you switch a large LED screen on and off safely?

Large LED screens should be powered on in stages and switched off in a controlled order, ideally automatically. Switching dozens of power supplies at once creates a large inrush current that trips breakers and stresses components.

A power sequencer or timed contactors bring sections of the screen on one after another. Many installations also use scheduled on and off times, so the screen runs only when needed — for example during opening hours — which saves energy and reduces wear. Brightness schedules or ambient light sensors reduce both power draw and heat.

Before handover, we test the screen’s behaviour through a deliberate power interruption: does it restart cleanly, does content resume on schedule, and does the control system recover without anyone touching it. If you are planning a screen and are unsure about your site’s supply, ask us to check it during a free site survey.

Common questions

Where to go next

More in Installation, Power & Maintenance