Power outages, voltage dips, and power peaks: the three electricity problems production actually feels

When operations managers talk about risk in the electricity supply, the conversation often centres on a total power outage: the power disappearing completely. That is also the most dramatic scenario. In day-to-day operations, though, it is less often that type of incident that actually stops production. More often it is short-lived, less visible disturbances that never appear in an outage statistic.

This article covers four electricity problems a manufacturing company can encounter: total power outage, voltage dips, frequency fluctuations, and power peaks, plus a fifth, related challenge: limited grid capacity. The aim is to show that it is not only the one large scenario that matters, and to point to where an industrial BESS can contribute directly, and where more is required.

Total power outage: the scenario everyone knows

A total power outage is when all or part of a site loses supply completely, typically because of a fault on the local electricity grid or planned interruptions linked to maintenance. The consequence is unambiguous: equipment that is not supplied from another source stops.

This is also where the terms emergency power, backup, generator, UPS, and BESS typically come up, because it is the scenario most people associate with "risk to production." A grid-connected BESS does not, however, automatically supply the site when the grid disappears. A battery connected to the collective electricity grid is, by default, designed to disconnect its own exchange with the grid during a fault, for the safety of anyone working to repair it. Keeping selected loads running during a power outage therefore requires a deliberate, separate technical solution on top of the basic system. It is not something that comes automatically.

Voltage dips: the incident that does not count in the statistics

Voltage dips take up far less space in the debate, but production often feels them more directly. According to the standard DS/EN 50160, a voltage dip is a short-lived reduction in voltage, where the measured voltage at the connection point falls to between 5 and 90 percent of normal for a period from 10 milliseconds to one minute, as described in Energinet and Green Power Denmark's information material on voltage dips. Typical causes include lightning strikes, weather, external influences such as excavation damage or animals on overhead lines, ageing assets, procedural errors, or faults abroad that propagate into the Danish system.

For an ordinary consumer, it feels like a brief "blink in the lights." For industry, the picture is different: voltage dips can stop processes precisely because they are so short and frequent that they are rarely recorded as "interruptions," yet still enough to knock out sensitive equipment such as PLC controls, frequency converters, and other automated control systems. A documented review of PLC-based control systems shows that a voltage dip down to around 75 percent of normal voltage for just five grid cycles, roughly 100 milliseconds, can stop an automated production system, even though a comparable older, hard-wired relay-controlled system would not have reacted to the same incident, according to a technical review of PLC sensitivity to voltage dips. Digital input modules in a PLC can react to a voltage change in as little as about 11 milliseconds, faster than one grid cycle, and the control system can therefore misinterpret the incident as a real stop before a person notices that the lights blinked. Frequency converters that control motor speed rest on the same type of sensitive electronics and can, for the same reason, respond unpredictably to a dip they are not sized to ride through.

Voltage dips are measured at the customer's connection point, while what happens inside the company's own installation lies outside the grid company's control. The consequence therefore depends on the time of day, the season, and which equipment is running when the incident occurs, not only on the size of the dip itself.

Frequency fluctuations: a system-level problem

Frequency fluctuations belong to another category. Where voltage dips and power outages typically arise locally, frequency is about the balance of the entire electricity system. There must at all times be balance between demand and generation, and that balance stabilises the system frequency around 50 Hz, which supports security of supply, as Energinet describes in its review of system services. To keep the balance, Energinet (Denmark's transmission system operator) purchases system services: flexible generation and demand that are adjusted up or down as needed. Demand units such as batteries can adjust in both directions, while wind turbines and solar PV can only be regulated downward, because generation depends on the weather. The need for system services is, according to Energinet's own forecast, expected to rise markedly in the coming years as a larger share of electricity generation comes from wind and solar, which contribute less than traditional power plants to the system's natural stability.

It is in that context that batteries are described as fast flexibility resources. Battery storage is one of the most versatile technologies for delivering short-term flexibility in the electricity system, because a battery can respond quickly and support system balancing. It is important, though, to keep two things separate: that a battery can help stabilise the electricity system as a whole is different from delivering emergency power to the individual company's own site. The first is a property of the technology and a role in a market Energinet operates. The second requires a separate, deliberately designed solution for the specific installation.

Power peaks and grid capacity: when peak load becomes more expensive and the installation is strained

Power peaks arise when the company, for short periods, draws markedly more power than it does on average, typically because several large loads such as motors, compressors, cooling plant, or furnace processes start or run at the same time. That has gained increasing economic importance, because more Danish grid companies have moved to making part of the grid tariff depend on power (kW) rather than solely on consumption (kWh). From the turn of the year 2024 to 2025, Cerius-Radius introduced a tariff model under which large customers on the 10 kV grid or above pay a power charge calculated as the average of the 10 hours with highest consumption over the past 12 months, approved by Forsyningstilsynet (the Danish Utility Regulator). From 1 January 2026 the principle is extended: for customers with industrial self-generation or a direct line between generation and consumption, 75 percent of the charge becomes power-based and only 25 percent consumption-based. Similar principles form part of several Danish grid companies' tariff models under the industry-approved Tarifmodel 3.0.

Repeated peak loads also strain main switchboards, cables, and transformer capacity, which can put physical pressure on how close the installation is operated to its capacity limit, independently of the tariff. That connects to a related challenge: that the company cannot obtain the power it wants at all without an upgrade of the grid connection. Pressure on Danish grid capacity is currently considerable. Energinet has stated that a sharp rise in applications for new connections has left very limited spare capacity in the transmission grid, driven among other things by large demand projects such as data centres, batteries, and Power-to-X plants. For many new customers, further grid reinforcement is required, and for the very largest connections the time horizon can stretch over 5 to 10 years. The answer to "can we get more power?" is therefore not always yes or no, but often "not without an upgrade, and not without waiting time."

What a BESS can address directly, and what requires more

There is a clear mechanical limit to what a battery can and cannot do, independently of which commercial model sits on top. An industrial BESS can mechanically discharge for short periods to cover part of peak demand, which directly reduces the power peak. In some cases that can both dampen the consequence of a power-based tariff and make it possible to use an existing grid connection better, provided there is in fact spare capacity outside the peak periods, which can then defer the need for an upgrade. Batteries are, as a technology, also documented as one of the fast resources that contribute to balancing and system services at electricity-system level.

Two of the problems lie outside what a standard system solves on its own. Protecting selected critical loads against a total power outage requires that the system is deliberately designed to continue supplying part of the installation even when the collective grid is gone. That presupposes additional components and a concrete analysis of which loads should be prioritised, and for how long supply must be maintained. It is an optional add-on that requires separate technical design, not a standard function. Protection against voltage dips for the most sensitive individual components, the type of sub-second protection a PLC or frequency converter needs, typically requires equipment sized specifically for the task, closer to the load itself. A large battery behind the main meter is not the same as a UPS at the individual control panel. Assuming that one automatically covers the other is one of the most widespread misunderstandings about BESS in production environments.

Why measured data is the first step

Common to all five problems is that you cannot know how exposed your own site is without looking at your own data first. That applies concretely to power peaks, where tariffing today is calculated directly from the company's own hourly values, and to voltage dips, where the consequence depends on the time of day, the season, and which equipment is running when the incident hits, and therefore can only be assessed from the company's own measurements, not from a nationwide statistic. An assessment of which of these problems are actually relevant for a given company should always start with the power profile across the day and the year, a history of known incidents, and knowledge of which equipment is most sensitive. Without that basis, any discussion of backup, peak shaving, or grid capacity is in practice a guessing game.

ZynexGroup's approach to system assessment

We always start with the company's own data, not with the system: the size of the grid connection, the power profile across the day and the year, and the knowledge the company already has about historical incidents and sensitive equipment. On that basis we can have a data-based dialogue about which of the problems this article covers are actually relevant at your particular site, whether an industrial BESS in the standard model can help reduce power peaks and use the existing grid connection better, and whether there is a concrete reason to look more closely at add-ons such as reserved capacity or supplementary equipment to protect sensitive loads.

Overall perspective

A total power outage is the most visible electricity problem, but far from the only one. Voltage dips can stop sensitive automated equipment without ever appearing in an outage statistic, frequency fluctuations are about the balance of the entire electricity system, and power peaks and grid capacity have become a direct economic and technical factor for many companies. An industrial BESS can mechanically address power peaks and in some cases support better use of existing grid capacity, while protection against a total power outage and against voltage dips for the most sensitive components requires separate design and typically supplementary equipment. The starting point for assessing what makes sense where is the same every time: own measured data, not assumptions.

Let us assess the potential for your facility

If you want to know which of these problems are actually relevant for your production, the starting point is your own data: grid connection, power profile, and any history of voltage dips, power outages, or other operating disturbances. We use that type of data for an initial assessment of whether there is a match between your situation and an industrial BESS, and what the next step would be if so. You are welcome to contact us here.