PRC-002 & PRC-028 Disturbance Monitoring Compliance

Monitoring-location analysis, recorder selection, channel and trigger design, time synchronization and data-retrieval architecture for Transmission Owners and Generator Owners — including inverter-based resources under PRC-028.

When a fault clears or a plant trips offline, the first question from the Regional Entity, the Reliability Coordinator or your own engineers is the same: what did the recorders see? Disturbance-monitoring compliance is not a paperwork exercise. It is a working recording system — the right quantities, at the right locations, stamped to a common clock and retrievable on request. Keentel Engineering designs that system and documents it so the recording architecture itself becomes the compliance evidence.

BES bus identification using the standard’s attachment methodology, with owner notifications and re-evaluation records
Sequence of events, fault and dynamic disturbance recording design using DFRs, relays and PMUs
GPS, IRIG-B and PTP time-source design and verification
PRC-028 recording readiness for solar, wind and BESS plants, including ERLPhase TESLA 4000 and SEL RTAC integration

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SER
FR
DDR

SER · FR · DDR

Three recording types engineered and documented

4–
765

4 kV–765 kV

Substation and plant voltage range supported

PRC
002→030

PRC-002 → PRC-030

From recording to IBR event analysis

All 6

Regional Entities supported

About Keentel Engineering

Your Trusted Partner in Electrical Engineering and Power Systems

At Keentel Engineering, we deliver electrical power engineering services built on 30 years of experience and a commitment to excellence. Our clients include utilities, developers, EPCs, and public agencies across the U.S.

Unlike firms that sacrifice technical depth to chase billable hours, we prioritize precision, compliance, and value engineering. From transmission services and relay modeling to winterization and SCADA planning, we never compromise on quality.

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Client-Focused Work Approach

At Keentel Engineering, we take pride in being the go-to electrical power engineering firm for power and utility system planning, substation design, protection, control, and power system analysis. The following attributes distinguish our team in utility-grade substation engineering and compliance-driven project delivery.

30 Years of Experience

With three decades of hands-on project delivery, we bring unmatched expertise in substation layout design, substation electrical and civil engineering, relay protection, and grid-tie solutions. Our experience includes projects in complex terrain, urban retrofit environments, and utility-scale renewable integrations.

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Our engineering process applies AutoCAD 3D, BIM modeling, and system-level substation design practices to ensure accurate planning, reduced errors, and efficient coordination across all project stakeholders.

Our workflow includes 3D substation design, enabling clash-free coordination between structural, electrical, and civil disciplines.

Attention to Detail

From grounding grid studies to relay protection settings, we engineer every detail to improve system reliability, performance, and operational safety. Our rigorous QA/QC process ensures compliance with IEEE, NFPA, and ISO/TSO interconnection standards.

Among leading electrical substation design companies, Keentel Engineering stands out for 30+ years of proven high-voltage and utility-grade project delivery.

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Disturbance Data Is How the Grid Learns From Events

Every significant system event is reconstructed from recorded data. Planners use it to validate models, protection engineers use it to confirm relays operated correctly, and event analysts use it to find out why a plant reduced output or tripped. Without time-aligned records from the right places, an event cannot be explained, and a misoperation or an unexpected inverter response cannot be corrected.

Two NERC standards set the recording obligations:

PRC-002 — Disturbance Monitoring and Reporting Requirements. Establishes sequence of events recording (SER), fault recording (FR) and dynamic disturbance recording (DDR) at identified BES locations, with time synchronization, data retention, data provision and restoration requirements for Transmission Owners and Generator Owners.
PRC-028 — Disturbance Monitoring and Reporting Requirements for Inverter-Based Resources. Extends disturbance monitoring to inverter-based resources, so the behavior of solar, wind and battery plants during grid disturbances can be captured and analyzed.

Confirm the versions in effect and their implementation plans for your registered functions and facilities before scoping work. PRC-028 in particular uses a phased implementation, and different facilities may reach their compliance dates at different times.

A recorder that is installed but not triggering, not time-synchronized or not retrievable is not compliance. Evidence starts with an engineered recording design and ends with data you can actually produce.

Electrical faults in a power system relevant to PRC-002 and PRC-028 disturbance monitoring, event reconstruction and recorded fault analysis

How PRC-002 Assigns Recording Obligations

PRC-002 works in two tracks: SER and FR data at BES buses selected by a defined methodology, and DDR data at Elements identified by the Responsible Entity. Both tracks share requirements for time synchronization, data retention, data provision and restoration of failed capability.

BES bus identification and owner notification

The Transmission Owner applies the bus-selection methodology in the standard’s attachment to identify the BES buses where SER and FR data is required. The methodology is based on available short-circuit levels and ranks candidate buses so that recording is concentrated where faults have the greatest system significance. The TO then notifies the other owners of BES Elements connected to those buses — including Generator Owners — that recording is required for their Elements, and re-evaluates the list on the cycle the standard specifies.

Most findings in this area are procedural: a list that was never re-run after system changes, a missing short-circuit basis, or no record that a connected owner was notified. We rebuild the calculation from a current short-circuit model and keep the methodology, results and notifications together.

Sequence of events and fault recording

At identified buses, the owners of the applicable Elements must capture SER data for circuit breaker position changes and FR data for the electrical quantities the standard lists, with the recording characteristics and trigger conditions it specifies. Generator Owners are responsible where the notified Elements are theirs, typically GSU high-side breakers and associated quantities.

Dynamic disturbance recording

DDR captures slower, longer-duration phenomena — frequency and voltage excursions, power swings and oscillations — rather than fault waveforms. The Responsible Entity identified in the standard (the Planning Coordinator or Reliability Coordinator) identifies the BES Elements where DDR data is required and notifies the owners. Owners then install and maintain DDR capability for those Elements with the recording characteristics the standard specifies.

Time synchronization, retention, provision and restoration

Time synchronization

recorded data must be time-synchronized to Coordinated Universal Time within the tolerance the standard specifies (±2 ms in PRC-002-2 and later), with the local time offset documented

Retention

SER, FR and DDR data must be retained for the minimum period the standard specifies (10 calendar days in the current version), counted from the recorded event

Provision on request

data must be provided to the RC, Regional Entity or NERC within the time frame the standard sets, in the format the standard specifies

Restoration

when recording capability fails, the owner must restore it within the time frame in the standard (90 calendar days in the current version) or submit a Corrective Action Plan and implement it

Confirm every numeric tolerance and timeline against the version in effect for your facilities; the values above reflect our reading of the current standard and are not a substitute for it.

What Each Recording Type Captures — and Where It Comes From

Choosing the right source for each recording type is the first engineering decision. A modern substation or plant may meet all three from different devices, and the channel list must show which device satisfies which requirement.

Recording type	What it captures	Typical source devices
Sequence of events (SER)	Time-stamped changes of state — breaker position, and where configured, relay trips, alarms and scheme operations — used to establish the order of events	Microprocessor relays, DFR digital inputs, RTACs and data concentrators with time-stamped status points
Fault recording (FR)	High-resolution voltage and current waveforms before, during and after a fault, triggered by defined conditions	Digital fault recorders (for example ERLPhase TESLA 4000), relay oscillography where it meets the required characteristics
Dynamic disturbance recording (DDR)	Continuous or long-duration records of frequency, voltage, current and power flows for swings, oscillations and frequency events	DFRs with continuous recording, phasor measurement units (PMUs), multifunction recorders
IBR plant-level recording (PRC-028)	Fault and disturbance records at the plant’s point of interconnection or main power transformer high side, as the standard specifies	Plant DFR, high-side relays, revenue-class or power-quality meters with recording, PPC data logs
Inverter-level data	Inverter fault codes, operating state, ride-through behavior and trip causes that explain plant response	Inverter and OEM data loggers, SCADA historians, plant controller event logs

Relay oscillography can be a legitimate source — if you can prove it. Sample rate, record length, triggers, channels and time stamping all have to be documented against the standard for each device you rely on.

Disturbance Monitoring Built for Solar, Wind and Storage

FERC Order No. 901 directed NERC to develop Reliability Standards for inverter-based resources covering disturbance monitoring, performance during disturbances, data sharing and model validation. PRC-028 came from the first phase of that work, alongside PRC-029 (ride-through) and PRC-030 (unexpected IBR event mitigation).

Repeated disturbance reports have shown that when IBRs reduce output or trip during grid events, the plant often lacks the recorded data needed to explain why. PRC-028 addresses that gap for Generator Owners of applicable IBRs.

What changes for IBR owners

Plant-level recording — SER, FR and DDR capability at the location the standard specifies, generally the high side of the main power transformer(s) near the point of interconnection
Inverter-level visibility — plant records alone rarely explain an inverter trip; retaining inverter fault codes and event logs is what makes a PRC-030 analysis possible
Time alignment across devices — plant recorders, relays, the power plant controller and inverter loggers need a common time reference so records can be compared
Retention and provision — data must be retained and provided on request as the standard specifies, which for many plants means rethinking where records are stored and who can retrieve them
Phased implementation — the standard phases compliance for existing IBRs over a multi-year period; confirm the dates and percentages that apply to your fleet in the implementation plan

The link to PRC-030

PRC-030 requires Generator Owners to identify unexpected reductions in IBR output during system events, analyze the cause and develop corrective actions. That analysis depends entirely on PRC-028 data. We design recording at IBR plants so that the same records support event detection, root-cause analysis and model validation under the MOD standards.

BESS in a solar power plant for PRC-028 inverter-based resource disturbance monitoring

What Our Disturbance-Monitoring Service Includes

Bus selection and notification package

Short-circuit-based application of the standard’s attachment methodology, results tables, owner notification letters and a re-evaluation schedule.

Device selection

DFR versus relay-based recording versus PMU trade-offs for each location, considering channel count, sample rate, continuous recording and storage.

Channel lists and trigger design

Voltage, current, residual and status channels mapped to each monitored Element, with trigger thresholds and record lengths documented against the standard.

Time-source design

GPS clocks, IRIG-B distribution and IEEE 1588 PTP architecture, holdover behavior, clock-failure alarms and the time-offset documentation auditors ask for.

Storage and retrieval architecture

SEL RTAC and data concentrator integration, automated record retrieval, secure remote access paths and central archiving sized for the required retention.

Commissioning and verification

Test-trigger procedures, channel polarity and scaling checks, time-sync verification and as-left configuration records.

PRC-028 IBR readiness

Gap assessment of plant recorders, inverter logging and PPC data against PRC-028, with an upgrade plan aligned to the phased implementation.

Data-request response procedures

Written procedures, roles and file-format conversion so a request from the RC, Regional Entity or NERC can be answered within the required time frame.

Engineering Decisions That Determine Whether the Data Is Usable

Most disturbance-monitoring problems are designed in, not caused by equipment failure. The decisions below are where we spend engineering effort.

Sample rates and record lengths

Fault recording needs enough samples per cycle and enough pre-fault and post-fault data to see the full event, including breaker failure and reclosing sequences. DDR needs long, continuous records at a lower resolution. We specify both against the standard’s minimum characteristics and against what your event analysts actually need, which is often more.

Triggers that fire when they should — and only then

Undervoltage, overcurrent, neutral overcurrent, frequency and rate-of-change triggers must be set so real events are always captured without filling storage with nuisance records. For IBR plants, triggers also need to catch the short voltage dips that cause momentary cessation or inverter trips.

Time sources you can defend

A single GPS clock with no monitoring is a common weak point. We design the time-distribution path — GPS receiver, IRIG-B or PTP distribution, device configuration and loss-of-sync alarms — and document the time offset and synchronization method, because time alignment is what lets records from different devices and different owners be compared.

Retrieval before retention

Retention requirements only matter if records reach storage. Automatic retrieval through an RTAC or data concentrator, with alarms for failed downloads and a secure remote access path, is what turns a recorder into a compliant recording system.

Protection and control engineering equipment supporting RTAC, DFR, SCADA and disturbance monitoring systems

Our PRC-002 and PRC-028 Process

Confirm applicability

Identify registered functions, applicable versions, facilities in scope and, for IBRs, where each plant sits in the phased implementation.

Establish required locations

Run or review the bus-selection methodology, confirm DDR Elements identified by the Responsible Entity and gather owner notifications.

Inventory existing capability

Document every recorder, relay, PMU and clock — model, firmware, channels, triggers, sample rate and time source — against the requirements.

Design the gaps closed

Specify new devices, channel additions, trigger settings, time-source upgrades and retrieval architecture, with drawings and settings.

Commission and verify

Test triggers, confirm channel scaling and polarity, verify time synchronization and retrieve sample records end to end.

Maintain readiness

Set up periodic verification, failure alarms, restoration tracking and data-request procedures so evidence stays current.

Deliverables and the Evidence They Provide

Deliverable	Evidence it supports
Bus-selection calculation and results	Application of the attachment methodology from a current short-circuit model, with the basis for each identified bus
Owner notification records	Dated notifications to owners of Elements at identified buses and DDR Elements
Monitored-Element and channel matrix	Which device records which quantity for which Element, mapped to each recording requirement
Recorder configuration and settings records	Triggers, sample rates, record lengths and as-left settings for each device
Time-synchronization design and verification	Clock architecture, synchronization method, offset documentation and test results
Data retention and retrieval architecture	Storage design, retrieval automation and retention confirmation
PRC-028 gap assessment and upgrade plan	IBR plant and inverter-level recording status against the standard and phased dates
Data-request and restoration procedures	Response workflow for requests and tracking for restoring failed recording capability

Recording Systems Designed by Engineers Who Use the Data

Substation and SCADA design depth

We design RTAC-based SCADA, DFR integration and time distribution as part of substation projects, so recording is engineered into the station, not added later.

Event analysis experience

Our protection engineers analyze relay and DFR records for PRC-004 and PRC-030, so we design recording around the questions event analysts actually ask.

IBR plant knowledge

We work with solar, wind and BESS plants on interconnection, EMT modeling and ride-through, which is where PRC-028 recording gaps usually sit.

Audit-team perspective

Former NERC audit-team leadership and SMEs know how bus lists, notifications, time sync and data provision are examined.

PRC-002 & PRC-028 Disturbance Monitoring Compliance — FAQs

1. Can we use relay oscillography instead of installing a DFR?

Often, yes. PRC-002 sets recording requirements, not a device type. If a relay captures the required quantities with adequate sample rate, record length, triggers and time stamping, it can be the source. The decision should be documented device by device, and many owners still choose a DFR where channel count, continuous recording or retrieval makes relays impractical.

2. We are a Generator Owner. Why did the Transmission Owner send us a PRC-002 notification?

The TO identifies BES buses where SER and FR data is required and notifies the owners of BES Elements connected to those buses. If your GSU or interconnection Elements connect to an identified bus, you are responsible for recording for those Elements as the notification describes.

3. How often does the PRC-002 bus list need to be re-evaluated?

The standard requires the Transmission Owner to re-evaluate the identified buses on a defined cycle and notify owners of changes. Short-circuit levels change as generation, lines and transformers are added or retired, so the underlying calculation should be refreshed with a current model each cycle.

4. Who decides where dynamic disturbance recording is required?

The Responsible Entity named in PRC-002 — the Planning Coordinator or Reliability Coordinator — identifies the BES Elements for which DDR data is required and notifies the owners. Owners then provide and maintain DDR capability for those Elements.

5. What time source should we use for disturbance recorders?

A GPS-disciplined substation clock is the usual reference, distributed by IRIG-B or IEEE 1588 PTP depending on the devices. What matters for compliance is meeting the standard’s synchronization tolerance, documenting the time offset and detecting loss of synchronization so it can be corrected.

6. What happens if a recorder fails?

PRC-002 requires the owner to restore recording capability within the time frame the standard specifies or submit and implement a Corrective Action Plan. A failure alarm, a tracking log and a record of the restoration date are the evidence that the requirement was met.

7. Does PRC-028 replace PRC-002 for solar, wind and battery plants?

PRC-028 establishes disturbance-monitoring requirements specific to inverter-based resources. How it interacts with PRC-002 for a given plant depends on the versions in effect and their applicability sections, so confirm both for each facility rather than assuming one replaces the other.

8. Why does inverter-level data matter if we record at the high side?

High-side records show what the plant did as a whole. They rarely show why. Inverter fault codes, operating state and event logs identify which inverters tripped or ceased current and the protective function responsible — the information a PRC-030 analysis and corrective action depend on.

9. Can we meet PRC-028 with our existing plant SCADA historian?

Usually not by itself. SCADA historians typically store data at intervals far too slow to capture fault or ride-through behavior. They are useful for context and inverter status, but plant-level fault and disturbance recording normally needs a DFR, suitable relays or a recording meter with the characteristics the standard requires.

10. Is CIP included in this service?

No. This service covers Operations & Planning disturbance-monitoring standards. We design secure retrieval paths as good engineering practice, but CIP cybersecurity compliance is a separate discipline that Keentel does not offer.

Keentel’s Grid IQ

PRC-002-5 and PRC-028-1 Compliance Explained for GOs and TOs

TESLA 4000 and NERC PRC-028 Compliance

NERC Compliance for Substations: RTACs, DFRs, Clocks and Protection Devices

PRC-030-1 Event Detection

SEL-3555-2 RTAC Substation SCADA Design

IBR time synchronization using GPS IRIG-B and PTP for disturbance monitoring compliance

The ±1 Microsecond Question: Time Synchronization for IBR Disturbance Monitoring Compliance

Make Sure the Recorders Capture the Next Event

Send us your bus list, recorder inventory and one-line diagrams. Keentel will check them against PRC-002 and PRC-028, design what is missing and document a recording system you can produce data from on request.

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