GridShepard

Engineering software for power systems

GridShepard · Software for power-system engineering

One engineering record for the studies, settings, tests and events of a power system.

GridShepard makes GridSentinel, an engineering suite that runs inside your network, and a field app for the technicians who test the equipment. Both are for people who must explain, later, why a setting is what it is and who signed off the test that proved it.

Illustrative one-line diagram A 115 kV source feeds disconnect 89-1, breaker 52-H and a delta to grounded-wye transformer T1, then main breaker 52-M onto a 13.8 kV bus. Current transformers on both sides of T1 feed a transformer differential relay, 87T. Three feeder breakers, 52-01, 52-02 and 52-03, each have a current transformer and an overcurrent relay, 51. Feeder breaker 52-01 is highlighted. A legend explains the symbols. 115 kV source 89-1 52-H CT T1 115/13.8 kV Δ–Y grounded CT 87T 52-M 13.8 kV bus 1 52-02 52-03 51 51 Feeder 2 Feeder 3 52-01 51 Feeder 1 Figs. 2–4 Breaker Disconnect Relay CT Relay wiring
Fig. 1 An illustrative substation, not a real facility. GridSentinel keeps every study, setting, test and event against equipment like this. Breaker 52-01 is followed through the figures below.

1The suite

GridSentinel

An internal engineering suite in seven areas, held together by one model of the equipment. It runs on your network, against your database and evidence storage.

Power-system work is spread across tools that do not know about each other: studies on a shared drive, settings in vendor software, test results in spreadsheets, event records in someone’s inbox. The trouble starts when a question crosses them.

GridSentinel keeps that work against the same equipment model. A question about breaker 52-01 can be answered from the study that coordinated it, the settings that protect it, the tests that proved it and the events it has cleared, with the reviews and signatures attached to each.

Illustrative time-current coordination curves Log-log plot of operating time against current. The 52-01 feeder relay curve sits below the 52-M main relay curve and the T1 transformer curve. At 3,000 amperes the margin between the feeder and main curves is marked. 10 100 1k 10k Current, A (13.8 kV base) 0.01 0.1 1 10 100 1000 Time, s Δt 3 kA fault T1 52-M 52-01
Fig. 2 Coordination from a system study: the 52-01 relay must clear before the main breaker and inside the transformer curve. Illustrative curves.
Illustrative event record Oscillography for feeder 52-01. Phase A current rises sharply at the fault, the overcurrent element picks up, the trip output asserts, and the breaker opens, after which all currents fall to zero. IA IB IC 51P TRIP 52A fault cleared
Fig. 3 Event record for 52-01, one division per cycle, reviewed against the settings in force and annotated. Synthetic waveform.

Schedule of product areas

No.AreaWhat it coversLimits
1.1System studiesShort-circuit, coordination with time-current views, arc-flash labels, on a versioned site model.Methods, inputs and deliverables need a qualified engineer’s review.
1.2Protection and eventsTrip and event review, annotations, relay-setting checks, PRC-030 analytics.Analytics support an engineer’s review. They do not decide a cause.
1.3Assets and maintenanceEquipment registry, due work, PRC-005 templates, test evidence, signatures.Intervals and procedures are set by the asset owner.
1.4Power qualityMonitoring points, data coverage, limit checks, violation review, monthly reports.Limit tables and source formats are verified per site.
1.5Switching and trainingSwitching-order preparation, connectivity views, a separate training simulator.Nothing here operates equipment.
1.6Settings and controlsRelay-setting comparison and a Git history of collected RTAC configurations.Read only. Never writes settings to a device.
1.7Reports and governanceReport packages with roles, review and release steps, and access logs.Retention and permissions are set per deployment.
1.8Field appTests recorded at the equipment and approved in GridSentinel. See Section 2.In development. Not yet validated on field hardware.

2The eighth area

The field app

A tablet app for recording maintenance tests at the equipment, written for gloved hands and for places with no signal.

Illustrative field app screen on a rugged tablet A rugged tablet shows one reading. A dark banner says the tablet is offline, the reading is saved and two items are waiting to send. The screen asks for contact resistance, phase A, on breaker 52-01, reading 1 of 3. The entered value is 52.4 micro-ohms; the previous value, 49.8 micro-ohms, is shown faintly. A status line says the value is within the example limit of 100 micro-ohms. Large Back and Next buttons sit at the bottom. Offline · saved on tablet 2 to send 52-01 · Feeder 1 1 of 3 Contact resistance Phase A · DLRO, 100 A 52.4 µΩ Previous: 49.8 µΩ (last test) Within example limit ≤ 100 µΩ Back Next: B Illustrative Bluetooth keypad with large keys for digits, decimal point, delete and enter 789 456 123 .0DEL ENTER
Fig. 4 One reading per screen, on a rugged tablet with a paired Bluetooth keypad. Illustrative values; the limit shown is an example, not an acceptance criterion.

Maintenance testing happens in substations, in the cold, often in gloves and with no signal. Office forms make that harder: small boxes, many fields, a send button that fails silently. The field app is designed the other way round: one value per screen, the last result for comparison, and a plain statement of what is waiting to send.

Read the field app concept page

In development. Not yet validated on field hardware; see Section 4.

  1. 2.1

    Glove first

    Every control is large enough for a gloved hand.

  2. 2.2

    A physical keypad

    Real keys for numbers, so readings go in without looking at the glass.

  3. 2.3

    Works offline

    Work is saved on the tablet and sent when a connection returns, at most once a minute.

  4. 2.4

    Scan the equipment

    A QR code opens the right record, so the reading goes against the right breaker.

  5. 2.5

    One reading per screen

    It is hard to type into the wrong box when there is only one box.

  6. 2.6

    Flags on the spot

    A reading outside its limit is flagged while the technician can still retest.

  7. 2.7

    Supervisor approval

    A supervisor approves results in GridSentinel. The tablet never approves its own work.

  8. 2.8

    A closing checklist

    GridSentinel receives a closed job only after all of its tests have arrived.

3Architecture

How the pieces connect

GridSentinel stays inside your network. The connection to the field is opened from the inside, outbound only.

Connection diagram Tablets send work to a cloud inbox over HTTPS. Inside your network boundary, a connector polls the cloud inbox over outbound HTTPS and writes received work into GridSentinel. No connection is opened from outside into the network. Your network No inbound connections cross this boundary Field tablets offline queue Cloud inbox holds submissions Connector polls, then writes GridSentinel database and evidence storage HTTPS poll, outbound response Connection diagram: tablets send to a cloud inbox; a connector inside your network polls it outbound and writes to GridSentinel. Your network Field tabletsoffline queue Cloud inboxholds submissions Connectorpolls, then writes GridSentineldatabase, evidence HTTPS poll, outbound response
Fig. 5 The connector asks the cloud inbox for new work; the inbox never connects in. A test counts as received once GridSentinel has stored it.
  1. 3.1

    The internal core

    Studies, events, assets and reports run on your network, against your database and evidence storage.

  2. 3.2

    Configured integrations

    Optional sources and workers connect only to endpoints you approve, with your credentials.

  3. 3.3

    The field extension

    The cloud inbox holds submitted work until the connector collects it. Retention and identity need your review first.

4Status · revised October 2026

Status and limits

What this page does and does not claim.

The suite
Section 1 follows the current application. Availability depends on configuration, data, integrations and vendor licences.
The field app
In development. Not yet validated on field hardware; not for operational use until it is.
Standards
NERC PRC-005, PRC-030 and NETA MTS are named because the software follows their practices. Nothing here is a compliance determination.
Figures and customers
Every diagram, curve, waveform and value is illustrative, not from a real facility. This page names no customers and quotes no one.