Collecting Data for SKM PowerTools: What You Need and How to Get It

SKM PowerTools (PTW) is the analysis engine. It runs the short circuit calculations, the coordination study, and the arc flash analysis under IEEE 1584. What it cannot do is collect the field data that those calculations require. That part is still a field problem, and the quality of what comes out of SKM is bounded by the quality of what goes in.

This page covers what data SKM PowerTools needs for an arc flash study, where that data comes from in the field, how errors enter the process, and how 70Ez addresses the data collection step upstream of SKM entry.

What SKM PowerTools is

SKM PowerTools is power system analysis software developed by SKM Systems Analysis, based in Manhattan Beach, California. It has been a standard tool for electrical engineers in North America for decades. Most engineering firms that perform arc flash studies professionally either use SKM or have used it.

PTW performs a range of power system calculations: short circuit analysis, protective device coordination, arc flash analysis per IEEE 1584, load flow, motor starting, cable ampacity, and more. For arc flash work, the three core modules are the short circuit study, the coordination study, and the arc flash module.

The software builds a model of the electrical system from user-entered data. Every transformer, bus, cable, breaker, fuse, and load gets entered into the PTW database. The model reflects whatever data the engineer typed in. Accurate data in, accurate results out. Wrong data in, wrong results out. The software cannot distinguish between correct and incorrect input.

The data gap between field and software

SKM PowerTools does not connect to the field. There is no automatic scan of installed equipment, no wireless pull of nameplate data, no integration with facility management systems in most deployments. The data gets into the software because someone puts it there.

The traditional path: a technician collects nameplate data in the field, the data is transcribed to paper or a spreadsheet, and an engineer keys it into PTW element by element. On a facility with two hundred panels, MCCs, and switchgear sections, that manual entry takes days. Every keystroke is an opportunity for a transcription error.

This is the data gap that arc flash data collection tools address. The analysis software is mature and capable. The bottleneck is moving accurate field data into the software efficiently.

What SKM needs for arc flash analysis

Building a valid arc flash model in SKM PowerTools requires data across several element categories. Each category maps to specific PTW input screens.

Utility source data

SKM represents the utility as an infinite bus or a voltage source with source impedance. The key value is available symmetrical fault current at the point of delivery, or equivalent source impedance in per-unit or ohms. This comes from the serving utility in writing. Engineers should request the utility fault current data at the beginning of the project, not after field collection is complete, since it can take time to obtain.

Transformer data

Transformers are the most critical elements in the SKM model for fault current calculations. PTW needs: rated kVA, primary and secondary voltage in kV, impedance percentage from the nameplate (not from standard tables), X/R ratio, and winding connection type. The nameplate impedance is the value that matters. Standard impedance for a given kVA class is a starting point, but actual transformers vary, and using a standard value instead of the nameplate value introduces error into every fault current calculation downstream of that transformer.

Bus data

Each bus in the PTW one-line needs a nominal kV rating. Bus naming should match the facility's actual designation so results can be tied back to physical locations. Consistent naming conventions across the one-line, the PTW model, and the field data collection records are important for catching errors during model review.

Cable and conductor data

SKM calculates cable impedance from conductor size, material, length, number of conductors per phase, and conduit type. All five inputs affect the result. Length is the most frequently missing or estimated field. A cable run estimated at 100 feet that is actually 160 feet adds meaningful impedance, which reduces available fault current at the downstream bus and increases clearing time, which can significantly change incident energy.

Circuit breaker data

PTW needs manufacturer, model, frame size, rated current, and interrupting rating for every breaker. For electronic trip breakers, the as-found settings for long-time pickup, long-time delay, short-time pickup, short-time delay, and instantaneous pickup all feed the coordination study and affect arc flash results. These settings must be recorded as found in the field. The breaker may be set differently than the coordination study specifies, and the as-found settings are what governs the actual clearing time.

Fuse data

SKM has a library of fuse time-current curves from major manufacturers. The field data needs to identify the specific fuse type and manufacturer so the engineer can select the correct curve in PTW. Generic fuse data or an incorrect fuse type leads to wrong clearing time assumptions, which affects incident energy at the fused equipment and everything the fuse protects.

Motor data

Motors that contribute to fault current need to be modeled. In SKM, motor contribution is typically handled at the bus level by specifying the total connected motor kVA. For large individual motors above approximately 50 HP, PTW allows individual motor elements. The field data needs rated HP or kW, voltage, and full load amperes.

SKM PTW input fields and what to collect in the field

The table below maps SKM PowerTools input fields to the corresponding field data needed. Use this alongside the arc flash field data collection checklist for a complete field collection reference.

How errors in field data affect SKM results

Power system analysis software propagates errors through the model. An error in a transformer impedance value does not just affect the arc flash result at that transformer. It affects every fault current calculation at every bus the transformer feeds, which affects every breaker clearing time calculation for equipment downstream, which affects incident energy values throughout that section of the system.

Transformer impedance errors

This is the most consequential single data error in most arc flash models. If a 1000 kVA transformer with 5.75% impedance is entered as 5.0%, the available fault current at the secondary bus increases by roughly 15%. Every downstream calculation shifts. Labels that were accurate become inaccurate. The error is invisible unless someone compares the model input against the nameplate photograph.

Missing cable data

Cables that are not modeled or are modeled with zero length add no impedance to the circuit. That overestimates available fault current at the downstream bus and underestimates clearing time. The result is lower calculated incident energy values than the real system would produce. For long runs to remote panels, missing cable data can make the actual hazard significantly worse than the label indicates.

Incorrect breaker settings

Breaker settings directly control clearing time. A breaker with the instantaneous function set to a lower threshold than recorded clears faster than the model predicts, reducing actual incident energy relative to the calculated value. A breaker set higher than recorded clears slower, meaning the actual hazard is worse than the label shows. As-found settings must be recorded, not assumed from coordination study documentation.

Verifying data accuracy before entry

A data verification step before entering values into SKM catches most transcription errors before they propagate through the model. The verification process should:

• Compare each entered value against the nameplate photograph. Not the field notes. The photograph.
• Cross-reference transformer impedance against any available test reports from the manufacturer. Actual measured impedance on a factory test report is more reliable than the nameplate stamping in some cases.
• Compare cable lengths against as-built drawings where available. Flag significant discrepancies for field verification.
• Confirm that breaker settings recorded in the field match the coordination study's specified settings, and document any differences as as-found conditions.
• Verify bus naming consistency between the field records, the PTW one-line, and any existing drawings.

This verification step is easier when field data is organized in a structured format rather than handwritten notes. Structured digital records can be compared against the PTW database systematically.

How 70Ez supports SKM data collection

The data collection step feeds SKM PowerTools. 70Ez addresses that step directly. Field technicians photograph equipment nameplates using the app. The AI reads the nameplate and populates structured data fields for each equipment type: transformer kVA, impedance, voltages; breaker manufacturer, frame, trip rating; fuse class and rating; cable size and material.

The technician reviews the extracted values against the nameplate image on the device and confirms or corrects them in the field, where the equipment is still accessible. The data is organized by project, by equipment type, and by location. The engineer receives structured, exportable records designed to work with SKM PowerTools.

This removes the manual transcription step between field collection and PTW entry. The technician is verifying AI-extracted data in the field rather than hand-writing values and re-keying them later. For large facilities, this difference is significant. The arc flash study gets built on field-verified data rather than twice-transcribed values.

The analysis still requires the engineer. The arc flash study, the coordination study, and the arc flash analysis all require engineering judgment. 70Ez addresses the data collection step upstream of those analyses, where the time is spent and where the errors originate.