A short circuit is one of the most destructive phenomena within an electrical installation. In milliseconds, forces are released that can destroy components, jeopardise operational safety and - in the worst case - threaten the safety of persons. For the engineer and installation manager, short-circuit current is therefore not an abstract concept, but a crucial parameter in the design and management of the installation.
Can your installation withstand the maximum possible short-circuit current? And do your protective devices switch off in time, but only where necessary? Understanding short-circuit currents according to the IEC 60909 standard is the basis for a safe and reliable power supply.
Basically, a short circuit is a connection between two or more points with different potentials, where the impedance (resistance) is close to zero. As the current chooses the path of least resistance, the current increases to a multiple of the rated current in a fraction of a second. We then refer to this as the short-circuit current.
For a technical manager or engineer, however, "the" short-circuit current is not a singular number. To design an installation safely, we look at different values in the time domain, as defined in IEC 60909:
Blindly relying on data from deliveries a decade ago is a risk. Installations change: transformers are added, cable lengths change and motors are replaced by frequency-controlled drives. Each change affects the impedance of the grid and therefore the short-circuit current.
Consequences of incorrect estimation:
Situation: An industrial bakery expands with a new production line and installs a heavier transformer to supply power.
Problem: The existing main distributor was calculated at the time for a lower short-circuit capacity ( ). Due to the lower impedance of the new transformer, the potential short-circuit current rises above the limit of the existing circuit breakers.
Risk: In the event of a shutdown, switches fail, resulting in a devastating arc and weeks of downtime.
Solution: An advance simulation had shown that switches needed to be replaced either or current-limiting coils.
Although we simulate short circuits in calculations as static events, in practice the cause is often dynamic or human.
Nuance: The effect of motors. It is often forgotten that running motors (induction) briefly act as generators during a short-circuit. They feed the fault. In a plant with many large motors, this can make the total short-circuit current significantly higher than just the contribution from the mains (the transformer). This is explicitly included in the IEC 60909 calculation.
You cannot "solve" a short-circuit current once it is there; you have to design the installation so that it can safely shut off the current. This is a process of prevention by calculation.
Step 1: Short-circuit current calculation (Simulation): Measuring is knowing, but with short-circuit currents, measuring is not an option (unless you want to blow up the installation). We use advanced simulation software (such as Vision or NEPLAN) to digitally recreate the network.
Step 2: Selectivity analysis: After the calculation, coordination follows. We set the protection relays and circuit breakers so that their time-current characteristics perfectly match. The protection closest to the fault should trip first.
Step 3: Hardware measures: Does the analysis show that the short-circuit current is too high for your current installation? Then there are engineering solutions:
Use these steps to identify risk:
In complex situations, standard calculations are not enough. Engage us when:
Delve further into the technology behind a stable installation:
Selectivity analysis: ensure that only the right circuit breaker trips when a fault occurs.
Harmonic analysis: the impact of pollution on your capacity.
Power Quality Measurements: The basis for every simulation.
Voltage dips: Result of short circuits elsewhere in the grid.
Symptoms are often subtle until things go wrong. Look out for unexplained machine failures, flickering lights, cables getting hot or transformers buzzing. Also, if electronics (PLCs, drivers) fail earlier than the service life indicates, chances are that the power quality is insufficient. A Power Quality measurement provides the answer.
This is possible, provided you have a high-quality Power Quality Analyzer (according to IEC 61000-4-30 Class A) and the knowledge to interpret the data. Collecting data is easy; analysing the correlation between events, harmonics and your specific business processes requires specialist engineering knowledge. We are happy to support you in the analysis.
Not by definition. NEN-EN 50160 describes the minimum requirements for voltage at the grid operator's transfer point. However, modern equipment can be more sensitive and malfunction even if the voltage is within this standard. We therefore look beyond the standard: we look at the compatibility between your power supply and your connected load.
Peace of mind, certainty and insight. You get a clear diagnosis of the 'health' of your electrical installation. We pinpoint the cause of faults, enabling you to avoid unplanned downtime and reduce fire risks or unnecessary energy losses. You receive a concrete advisory report with practical points for improvement.
No, that is a misconception. A filter is a powerful tool, but not a panacea. Sometimes the solution lies in changing transformer settings, redistributing loads or adjusting cabling. HyTEPS always recommends a thorough analysis and simulation before we recommend hardware, to avoid unnecessary investments.
Yes, significantly. Solar panel inverters and LED lighting drivers are non-linear loads that cause harmonics and sometimes supraharmonics. This can lead to interference with other equipment or overloading of the neutral conductor. When renovating or preserving, a Power Quality check is essential to ensure operational reliability.
We call this phenomenon 'nuisance tripping'. Often the cause is not the total amount of current, but the distortion of the current (harmonics) or short peak currents that your measuring equipment misses. This contamination can extra heat up thermal protections or confuse electronic protections, causing them to switch off wrongly. A specialised measurement can find out exactly why a protection reacts.
For a reliable picture, we usually measure at least one to two weeks. This is necessary to capture a full duty cycle, including weekends and peak loads. For specific acute failures, we can also take short-term measurements or deploy 'continuous waveform recording' to capture transients.
Your installer is an expert in installation and maintenance (the 'general practitioner'). HyTEPS is the specialist (the 'Power Quality Doctor'). We have advanced measuring equipment, simulation software and in-depth knowledge of theoretical electrical engineering and regulations. We often work together with installers to solve complex puzzles that fall outside standard knowledge.
After the measurement, you receive a report with conclusions in understandable language as well as technical details. If necessary, we simulate the possible solutions in our software. So you know exactly what the effect of a measure will be in advance. We then supervise the implementation and verify the result with a follow-up measurement.
Do you doubt whether your protective devices are still calculated for the current situation? Don't take a risk with safety and reliability. Our engineers analyse your network configuration and provide a conclusive security plan.
HyTEPS
Beemdstraat 3
5653 MA Eindhoven
