Collecting Data for ETAP: What the Software Needs from the Field

ETAP is capable power system analysis software. For large industrial facilities and utilities with complex electrical systems, it is often the platform of choice. But ETAP does not collect data. Someone has to go into the field, record equipment nameplate values, and bring that data back in a form that the software can use. The quality of an ETAP arc flash model is determined entirely by the quality of that field data.

This page covers what ETAP needs for an arc flash study, where that data comes from, the most common data quality problems in ETAP projects, and how 70Ez addresses the data collection step that feeds ETAP entry.

What ETAP is

ETAP (Electrical Transient Analyzer Program) is enterprise power system analysis software developed by Operation Technology, Inc. (OTI). It is widely used by electric utilities, large industrial facilities, oil and gas operations, and engineering firms internationally. ETAP has strong capabilities in areas that go beyond typical arc flash software: load flow analysis, motor starting studies, harmonic analysis, relay coordination for complex systems with microprocessor relays, and real-time power management in some configurations.

For arc flash work, ETAP runs short circuit analysis, protective device coordination, and arc flash calculations under IEEE 1584. It generates incident energy values, arc flash boundary distances, PPE requirements, and equipment labels. The study workflow is similar to SKM PowerTools and EasyPower, with differences in the interface and in how data is entered and organized.

ETAP's project structure is built around a one-line diagram. Engineers place electrical elements graphically and connect them to represent the actual power distribution system. Each element has a data editor where nameplate and configuration data is entered. The database stores everything. Studies run against that database.

The data problem is the same regardless of software

The choice of analysis software does not change the field data problem. ETAP needs the same fundamental data that SKM or EasyPower needs: utility source impedance, transformer nameplate values, cable parameters, circuit breaker data, fuse data, and bus ratings. The software interface is different. The underlying data requirements are not.

What does differ is that ETAP is more commonly used for systems with complex relay schemes. Facilities with microprocessor protective relays, digital fault recorders, and multi-zone protection systems have additional relay data requirements that go beyond simple breaker settings. ETAP's relay database supports detailed modeling of relay characteristics. Getting the relay settings out of the field and into ETAP correctly requires the same careful data collection as any other element.

The field technician cannot use ETAP to speed up the collection. The data still comes from nameplates, relay front panels, and existing documentation. What changes the collection speed is the field tool, not the analysis software.

What ETAP needs for arc flash analysis

Utility source data

ETAP models the utility as a power grid element with source impedance. The engineer needs available fault current at the point of interconnection or equivalent source impedance in per-unit. This comes from the serving utility in writing. For systems at medium voltage or above, the utility may provide separate values for maximum and minimum fault conditions. Both are useful for different aspects of the study.

Transformer data

ETAP's transformer data editor accepts: MVA or kVA rating, primary and secondary voltage in kV, impedance percentage from the nameplate, X/R ratio, tap settings, and winding connection. The impedance and X/R ratio from the nameplate should always be used over standard values. Actual transformers vary from the standard impedance for their rating class. That variance is meaningful for fault current calculations at every bus the transformer feeds.

Bus data

Every bus in the ETAP one-line needs a nominal voltage, a bus name or ID, and a type designation (swing bus, generator bus, or load bus). Bus naming should be consistent with physical equipment labels in the facility. Inconsistent naming creates confusion during model review and when tying study results back to physical equipment for labeling.

Cable and conductor data

ETAP calculates cable impedance from conductor specifications. The inputs needed: conductor size (AWG or kcmil), conductor material (copper or aluminum), insulation type, number of conductors per phase, length, and conduit type (magnetic steel, non-magnetic aluminum, or PVC). All of these affect the calculated impedance. Length is the most commonly missing or estimated field, and it is one of the more consequential inputs for long runs feeding remote equipment.

Circuit breaker data

ETAP needs manufacturer, model, frame size, rated current, and interrupting rating for every breaker. For electronic trip breakers, the complete trip unit settings are required: long-time pickup, long-time delay, short-time pickup, short-time delay, instantaneous pickup, and ground fault settings if applicable. These must be the as-found settings read from the breaker, not the values from a coordination study specification. Discrepancies between specified and as-found settings should be documented and flagged.

Protective relay data

For systems with electromechanical or microprocessor protective relays, ETAP needs relay manufacturer, model or relay type, CT ratio, pickup setting, time dial setting (for overcurrent relays), and instantaneous setting. Microprocessor relays may have multiple protection functions (overcurrent, differential, distance) with independent settings for each. The field data collection scope for relay-protected systems is significantly larger than for breaker-only systems.

Fuse data

Fuse data requirements are the same across platforms: manufacturer, fuse type or class, current rating, voltage rating, and interrupting rating. ETAP's fuse library requires selecting the specific manufacturer and model to apply the correct time-current curve. Generic fuse selections produce inaccurate coordination and arc flash results.

Motor data

Motors contributing to fault current are modeled in ETAP with rated HP or kW, nameplate voltage, and full load amperes. Large individual motors get their own element in the one-line. Smaller motors are often lumped at the bus level. The threshold for individual modeling versus lumped is typically based on motor size and the significance of the motor's contribution to fault current at that bus.

ETAP element data fields and what to collect in the field

Download the free arc flash field data collection checklist for a complete field-ready reference covering every data point by equipment type. The table below maps ETAP element types to the key data fields and what to collect in the field for each.

Common data quality issues in ETAP projects

ETAP models built from poor field data produce unreliable arc flash results. These are the most common quality problems and how they affect the output.

Cables modeled with zero or estimated length

When cable lengths are not measured or not available from drawings, engineers sometimes model cables at zero length or use a rough estimate. Zero-length cables add no impedance to the circuit. That overestimates available fault current at the downstream bus. In some parts of a facility, the actual cable runs are long enough that this error materially changes the calculated incident energy.

Standard transformer impedance instead of nameplate values

ETAP has standard impedance values for transformer ratings. Using these defaults when the nameplate value is available is a common shortcut. Actual transformers are manufactured within a tolerance range. A 1000 kVA transformer with 5.75% impedance on the nameplate may default to 5.5% in ETAP's standard values. That difference affects fault current at every bus downstream of that transformer.

Relay settings from documentation rather than field readings

Protective relay settings in the field do not always match the coordination study specification or the relay settings sheet. Relays get adjusted, relays get replaced with different models, and settings change over time without documentation being updated. Using specification values instead of as-found readings means the ETAP model may not reflect the actual protective device behavior in the field.

Bus naming inconsistency

ETAP model bus names that do not match facility equipment designations make it difficult to trace study results back to physical equipment for labeling. When a label says "Bus 14A" and the facility calls it "MCC-2 Bus Section B," someone has to reconcile those names before labels can be applied. This adds time and introduces the possibility of labels being applied to the wrong equipment.

Cross-referencing field data against existing documentation

The most reliable approach to ETAP data quality is to verify field-collected nameplate data against original equipment documentation before entering it into the model.

• Compare transformer nameplate impedance against the manufacturer's factory test report if available. Factory test reports record the actual measured impedance, which is the most accurate value for the model.
• Cross-reference cable lengths against as-built drawings. Where discrepancies exist, prefer the measured field length over the drawing value, since cables are sometimes rerouted during installation.
• Compare as-found relay and breaker settings against the protection coordination study or settings sheet. Document differences. Flag them for the engineer to review before the model is finalized.
• Verify bus naming against facility equipment tags. Establish a naming convention before data entry begins and apply it consistently across the one-line, the field data records, and the ETAP database.

Facilities with current, accurate as-built drawings and organized equipment documentation can move through the data collection phase quickly. Facilities with outdated or incomplete records take longer, and the model built from those records will need more verification before the study can be signed off.

How 70Ez addresses the ETAP data collection step

The data collection step that feeds ETAP is where 70Ez operates. Field technicians use the app to photograph equipment nameplates. The AI reads the nameplate and populates the appropriate data fields for each equipment type: transformer kVA, impedance, voltage ratings; breaker manufacturer, frame, trip settings; cable size and material. The technician reviews the extracted values against the nameplate image on the device and confirms or corrects them before moving to the next piece of equipment.

The data is organized by project, by equipment type, and by location. When field collection is complete, the engineer receives structured records in formats designed to work with ETAP. The manual transcription step between field notes and ETAP data entry is removed.

For facilities with relay protection, the field collection scope is larger, but the same approach applies. The app captures relay model and settings data. The technician verifies. The engineer gets organized records that map to ETAP's relay database fields.

The arc flash study, the coordination study, and the arc flash analysis all require engineering judgment and licensed engineering sign-off. 70Ez addresses the upstream step, where most of the field time goes and where most of the model errors originate.