SKM PowerTools versus EasyPower: A Comparison for Commercial and Industrial Studies

Published: June 2026
Technical Level: Intermediate Category: Engineering Software

Abstract

SKM PowerTools and EasyPower are two of the established platforms for the power system studies that commercial and industrial electrical engineering requires — load flow, short-circuit duty, protective-device coordination, and arc-flash incident-energy analysis. This paper compares them on the basis of their analysis capabilities, their treatment of the ANSI short-circuit and IEEE 1584 arc-flash calculations that govern North American facility work, their modeling and coordination workflows, and the engineering contexts in which each is the more natural choice. Because both tools implement the same governing standards, the paper also makes those standards explicit: the asymmetric fault-duty calculation that sizes interrupting equipment and the IEEE 1584-2018 incident-energy model that sets arc-flash boundaries and PPE. Both tools produce results that, for a correctly constructed model, satisfy the same code requirements; the comparison therefore centers on workflow, usability, and the established practice of the engineering organization rather than on a disparity in fundamental analytical capability.

1. Introduction

The electrical engineering of a commercial building or an industrial facility requires a defined set of power system studies. A short-circuit study establishes the fault duty that equipment must interrupt and withstand; a coordination study sets the protective devices so that the device nearest a fault clears it while upstream devices hold, preserving selectivity; and an arc-flash study computes the incident energy to which a worker would be exposed and assigns the personal protective equipment and boundaries that NFPA 70E requires. These studies are mandatory for the safe and code-compliant design and operation of a facility, and they are performed in dedicated software. SKM PowerTools and EasyPower are two of the principal tools for this work in North American practice, and an engineering organization equipping itself for facility studies must choose between them or operate both.

Because the two tools implement identical governing standards, a meaningful comparison must begin by making those standards explicit. The sections that follow therefore state the two calculations that dominate facility study work — the asymmetric short-circuit duty and the IEEE 1584 arc-flash incident energy — and then examine how each tool's workflow lets an engineer build the model, run the calculation, and defend the result.

2. Analysis Capabilities

Both SKM PowerTools and EasyPower perform the full set of studies that facility work requires, and both implement the governing North American standards: the ANSI/IEEE C37 methods for short-circuit duty, the IEEE 242 and related practice for protective coordination, and the IEEE 1584 method for arc-flash incident energy. For a correctly constructed model of a given facility, both tools compute fault currents, coordination margins, and incident energies that satisfy the same code obligations, because both implement the same underlying standard calculations. The differentiation between them lies not in whether they can perform a required study but in how the engineer builds the model, conducts the study, and interprets and documents the result.

SKM PowerTools has a long-established position in industrial and commercial study work and is known for the depth and configurability of its analysis modules; engineers accustomed to its environment value the control it affords over the details of each study. EasyPower is known for an interface and workflow oriented toward efficiency, with automation of routine steps in coordination and arc-flash work that can accelerate the production of a study. Both approaches reach a compliant result; the difference is in the balance between fine-grained control and workflow efficiency, and the weight an organization places on each depends on the complexity of its typical projects and the experience of its engineers.

3. The Governing Calculations Both Tools Implement

The value of comparing two study platforms rests on understanding that neither invents its own physics: both reproduce the same standardized calculations, and the fidelity of a study depends on the inputs the engineer supplies rather than on a proprietary method. Two calculations dominate commercial and industrial facility work — the asymmetric short-circuit duty that sizes interrupting equipment, and the arc-flash incident energy that sets worker protection — and stating them explicitly clarifies exactly where each tool's workflow can help or mislead the engineer.

3.1 Asymmetric Short-Circuit Duty

The short-circuit study establishes the current an overcurrent device must interrupt. The symmetrical RMS fault current follows directly from the Thevenin impedance seen at the fault point, but the current an interrupting device actually experiences in the first cycles is larger because the fault current contains a decaying DC offset that depends on the X/R ratio of the circuit. The ANSI/IEEE C37 methods capture this through an asymmetry multiplier applied to the symmetrical value, and it is this asymmetric duty — not the symmetrical current alone — that governs equipment rating.

The asymmetric RMS fault current at a given time after fault inception is expressed as:

Iasym=Isym1+2 e−4πftX/RI_{\text{asym}} = I_{\text{sym}} \sqrt{1 + 2\,e^{-\frac{4\pi f t}{X/R}}}

Where:

IasymI_{\text{asym}} is the asymmetric RMS fault current in amperes.

IsymI_{\text{sym}} is the symmetrical RMS fault current from the Thevenin impedance in amperes.

ff is the system frequency in hertz (60 Hz in North American practice).

tt is the time after fault inception in seconds at which the duty is evaluated.

X/RX/R is the ratio of reactance to resistance of the circuit at the fault point.

In practice the X/RX/R ratio is the term that most often catches an engineer: a high X/RX/R circuit — one dominated by transformers and reactors close to a strong source — decays slowly, so the DC offset persists and the asymmetric duty can substantially exceed the symmetrical current. Both SKM and EasyPower compute this multiplier automatically from the modeled impedances, which means an error in the assumed source impedance or transformer reactance propagates silently into an understated interrupting duty. The engineer's obligation is to verify the X/RX/R the tool derived, not merely to accept the asymmetric current it reports.

3.2 IEEE 1584 Arc-Flash Incident Energy

The arc-flash study computes the thermal energy a worker at the working distance would receive if an arcing fault occurred, and from that energy it assigns the arc-rated PPE and the arc-flash boundary that NFPA 70E requires. Under IEEE 1584-2018 the incident energy scales with the arcing current, the protective-device clearing time, and the working distance, so it couples directly to the coordination study: the clearing time that the arc-flash calculation consumes is an output of the time-current coordination the engineer has set.

In its normalized log-linear form, the IEEE 1584 incident energy is expressed as:

E=4.184  Cf  En(t0.2)(610xDx)E = 4.184 \; C_f \; E_n \left( \frac{t}{0.2} \right) \left( \frac{610^x}{D^x} \right)

Where:

EE is the incident energy at the working distance in joules per square centimeter.

CfC_f is a calculation factor (1.0 for voltages above 1 kV, 1.5 for 1 kV and below).

EnE_n is the normalized incident energy determined from the arcing current, electrode configuration, and gap per the IEEE 1584 model.

tt is the arcing-fault clearing time in seconds, taken from the protective-device coordination.

DD is the working distance from the arc to the worker in millimeters.

xx is the distance exponent, which depends on voltage class and equipment type.

The dominant lever in this relationship is the clearing time tt: because incident energy is linear in tt, halving the clearing time roughly halves the incident energy and can move a task from a high PPE category into a lower one. This is precisely why the arc-flash result cannot be trusted independently of the coordination study — an optimistic clearing time assumed in one and an aggressive setting made in the other can each, on their own, understate the hazard. Both SKM and EasyPower integrate the two so that a change to a protective setting propagates into the incident energy and the label; the engineer must still confirm that the electrode configuration and working distance the tool assumed match the real equipment, because those choices move the result as strongly as the clearing time does.

4. Coordination and Arc-Flash Workflow

The protective-coordination study, in which the engineer plots the time-current characteristics of each device on a common axis and adjusts settings to achieve selectivity, is central to facility work, and the two tools present this task somewhat differently. SKM's coordination environment offers detailed control over the characteristic curves and the settings, suited to the engineer who wishes to manipulate each device individually; EasyPower's coordination environment emphasizes a streamlined workflow with assistance in identifying and resolving coordination conflicts.

As illustrated in Figure 1, a coordination study is read as a family of time-current curves on log-log axes, with fault current increasing to the right and operating time increasing upward. The reader should observe the vertical separation between adjacent device curves: that gap is the coordination time interval, and it must remain positive across the full range of credible fault currents for the downstream device to clear first. Where the curves of an upstream and a downstream device cross or converge, selectivity is lost and both devices may operate together — the defect a coordination study exists to find. Both tools render this same plot; they differ in how much they assist the engineer in detecting and resolving those crossings.

Time-current coordination curves for a series of protective devices on log-log axes, showing operating time in seconds against fault current in amperes. The vertical separation between adjacent device curves represents the coordination time interval that must remain positive across the fault-current range to preserve selectivity; a crossing of two curves indicates a miscoordination where an upstream device may operate before the downstream device clears.

The arc-flash study, which under IEEE 1584-2018 computes incident energy from the arcing current and the protective-device clearing time, depends directly on the coordination results, and both tools integrate the arc-flash calculation with the coordination so that a change to a protective setting propagates to the incident-energy result and the resulting labels. Figure 2 shows how incident energy responds to the clearing time that the coordination study delivers. The reader should note the near-linear rise of incident energy with clearing time and the strong reduction achieved at the shorter working distances: this is the quantitative reason a small improvement in coordination speed, or a modest increase in working distance, can move a task into a lower PPE category.

Arc-flash incident energy in calories per square centimeter plotted against protective-device clearing time in seconds, with separate curves for representative working distances. Incident energy rises approximately linearly with clearing time and decreases as working distance increases, illustrating that faster protective clearing and greater working distance both reduce the thermal hazard to a worker.

For an organization producing many studies under schedule pressure, the efficiency of the workflow is a material consideration, and EasyPower's automation is valued in that context. For an organization undertaking complex studies in which the engineer must exercise detailed judgment over each device, the configurability of SKM is valued. Both produce the labels, reports, and documentation that NFPA 70E compliance requires, and the quality of the resulting study depends on the engineer's command of the standards as much as on the tool.

5. Selecting Between the Tools

The selection between SKM PowerTools and EasyPower is, for most organizations, governed by workflow preference, by the experience of the engineering staff, and by the established practice of the firm rather than by a difference in what the tools can compute. An organization whose engineers are experienced in SKM and whose projects reward fine-grained control over each study is well served by continuing with it; an organization seeking to accelerate the production of routine commercial and industrial studies may find EasyPower's workflow advantageous. Both tools maintain the standard implementations and the library of protective devices that facility work requires, and both are capable of producing fully code-compliant short-circuit, coordination, and arc-flash studies. The decisive factors are therefore the fit with the organization's workflow and the competence of its engineers in the underlying standards, not a gap in analytical capability.

6. Conclusion

The most consequential point for a firm choosing between these tools is that both implement the same governing methods — the ANSI asymmetric short-circuit duty of Section 3.1, the IEEE 242 coordination of Section 4, and the IEEE 1584 arc-flash model of Section 3.2 — so the decision is about workflow and staff, not about which produces a more defensible result. SKM rewards depth and configurability in the hands of experienced engineers running complex studies; EasyPower rewards an automated, streamlined workflow for the efficient production of routine studies. A firm that mismatches the tool to its actual project mix and staff experience pays for it in study throughput.

The most common implementation failure is trusting either tool's automation without auditing the inputs it automated — the X/RX/R ratio that drives the asymmetric duty, the electrode configuration and working distance that drive the incident energy, and the clearing times the coordination assigns — because the convenience that makes a tool fast is exactly what lets an unverified assumption propagate into a sealed study. As the incident-energy relation makes explicit, the clearing time enters linearly, so an optimistic coordination setting understates the hazard in direct proportion.

The engineer should next benchmark the two tools against the IEEE 1584-2018 validation test cases on a representative facility model, comparing not just the answers but the steps and the time each requires to reach them, so that the selection rests on a measured workflow comparison rather than on vendor positioning.

Related Work

The analysis in this paper connects to several companion studies in this library. Readers concerned with the upstream and downstream engineering will find ETAP and SKM PowerTools develops a closely related aspect of the same problem, while CYME and SKM PowerTools extends the treatment into an adjacent domain. For the broader methodological context, ETAP and EasyPower provides complementary depth.

References

[1] IEEE Standard 1584-2018, IEEE Guide for Performing Arc-Flash Hazard Calculations, IEEE, 2018.

[2] NFPA 70E-2024, Standard for Electrical Safety in the Workplace, National Fire Protection Association, 2024.

[3] IEEE Standard 242-2001, IEEE Recommended Practice for Protection and Coordination of Industrial and Commercial Power Systems (Buff Book), IEEE, 2001.

[4] IEEE Standard C37.010-2016, IEEE Application Guide for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis, IEEE, 2016.

[5] IEEE Standard 399-1997, IEEE Recommended Practice for Industrial and Commercial Power Systems Analysis (Brown Book), IEEE, 1997.

[6] NFPA 70-2023, National Electrical Code, National Fire Protection Association, 2023.