Real-Time Transmission Limits (Live)

THE LIVE PJM CONSTRAINT FEED — what is binding right now: the constraint name, its type, its contingency, and its shadow price, on a five-minute grid roughly 9 minutes behind real time.

Congestion & Constraints data PJM market

Query with the agent

Native record

event_time x constraint_name x contingency

every 5 minutes, 30-day retention publication cadence

Evidence

Observed market data

Published observations from the named source

Time basis

Point-in-time records

UTC · event_time

Overview

PJM only publishes a row when a constraint is actually binding, and only retains a rolling 30 days; for history, see pjm_rt_marginal_value (the same shadow-price concept, ~20h behind, retained to 2010). Its shadow-price column was added 2020-04-29 and was not backfilled before that date. Source: PJM Market Data.

Query contract

Preserve one canonical row per (event_time, constraint_name, contingency) before aggregating.

Analysis rules

Group only after preserving the declared grain: event_time, constraint_name, contingency.

Access

Query from your own tools

Use the guarded HTTP endpoint directly, or connect an MCP client and load the dataset contract with describe_data before calling query_data.

PJM MCP API reference

HTTP endpoint

POST /api/v1/datasets/pjm_transmission_limits/query

Schema6

Column

Type

event_timeDateTime64(6, 'UTC')

constraint_nameLowCardinality(String)

constraint_typeLowCardinality(String)

contingencyString

shadow_priceNullable(Float64)

ingested_atDateTime64(6, 'UTC')

Sample data

event_time	constraint_name	constraint_type	contingency	shadow_price	ingested_at
2026-09-19 18:35:00.000000	NOTTINGHM 1-3 SER DEV A 230 KV	Thermal	CONASTON 500 KV CONASTON 5012/500-4 GCB B;CONASTON 500 KV CONASTON 5012/3-500B GCB C;LINE 500 KV CONASTON-PEACHBOT 5012;PEACHBOT 500 KV PEACHBOT 235 CB;PEACHBOT 500 KV PEACHBOT 245 CB;	-498.24	2026-09-19 18:44:19.274873
2026-09-19 18:35:00.000000	Lake George - Tower Road 138 kV l/o Lake George - Babcock 345 kV	Thermal	BASE	-179.44	2026-09-19 18:44:19.274873
2026-09-19 18:35:00.000000	Kokomo - Tipton W. 230kV l/o Nucor - Cayuga 345kV	Thermal	CAYUGA2 345 KV CAYUGA2 01B9 CB;CAYUGA2 345 KV CAYUGA2 10-01 CB;LINE 345 KV NUCOR-CAYUGA2;NUCOR 345 KV NUCOR 01 CB;NUCOR 345 KV NUCOR B2 CB;	-64.12	2026-09-19 18:44:19.274873
2026-09-19 18:35:00.000000	ELIMSPOR-SUNBURY B 230 KV	Thermal	LINE 230 KV MONTOUR-SAEGERS MON-SAE;MONTOUR 230 KV MONTOUR MILTSAE1 CB;MONTOUR 230 KV MONTOUR SAEG1 CB;SAEGERS 230 KV SAEGERS CLN_MON CB;SAEGERS 230 KV SAEGERS MONT_1 CB;	-3.18	2026-09-19 18:44:19.274873
2026-09-19 18:30:00.000000	NOTTINGHM 1-3 SER DEV A 230 KV	Thermal	CONASTON 500 KV CONASTON 5012/500-4 GCB B;CONASTON 500 KV CONASTON 5012/3-500B GCB C;LINE 500 KV CONASTON-PEACHBOT 5012;PEACHBOT 500 KV PEACHBOT 235 CB;PEACHBOT 500 KV PEACHBOT 245 CB;	-302.36	2026-09-19 18:44:19.274873
2026-09-19 18:30:00.000000	Lake George - Tower Road 138 kV l/o Lake George - Babcock 345 kV	Thermal	BASE	-1457.7	2026-09-19 18:44:19.274873
2026-09-19 18:30:00.000000	ELIMSPOR-SUNBURY B 230 KV	Thermal	LINE 230 KV MONTOUR-SAEGERS MON-SAE;MONTOUR 230 KV MONTOUR MILTSAE1 CB;MONTOUR 230 KV MONTOUR SAEG1 CB;SAEGERS 230 KV SAEGERS CLN_MON CB;SAEGERS 230 KV SAEGERS MONT_1 CB;	-20.02	2026-09-19 18:44:19.274873
2026-09-19 18:30:00.000000	NOTTINGHM 1-3 SER DEV A 230 KV	Thermal	CONASTON 500 KV CONASTON 5012/500-4 GCB B;CONASTON 500 KV CONASTON 5012/3-500B GCB C;LINE 500 KV CONASTON-PEACHBOT 5012;PEACHBOT 500 KV PEACHBOT 235 CB;PEACHBOT 500 KV PEACHBOT 245 CB;	-302.36	2026-09-19 18:39:21.036596
2026-09-19 18:30:00.000000	Lake George - Tower Road 138 kV l/o Lake George - Babcock 345 kV	Thermal	BASE	-1457.7	2026-09-19 18:39:21.036596
2026-09-19 18:30:00.000000	ELIMSPOR-SUNBURY B 230 KV	Thermal	LINE 230 KV MONTOUR-SAEGERS MON-SAE;MONTOUR 230 KV MONTOUR MILTSAE1 CB;MONTOUR 230 KV MONTOUR SAEG1 CB;SAEGERS 230 KV SAEGERS CLN_MON CB;SAEGERS 230 KV SAEGERS MONT_1 CB;	-20.02	2026-09-19 18:39:21.036596
2026-09-19 18:25:00.000000	NOTTINGHM 1-3 SER DEV A 230 KV	Thermal	CONASTON 500 KV CONASTON 5012/500-4 GCB B;CONASTON 500 KV CONASTON 5012/3-500B GCB C;LINE 500 KV CONASTON-PEACHBOT 5012;PEACHBOT 500 KV PEACHBOT 235 CB;PEACHBOT 500 KV PEACHBOT 245 CB;	-237.6	2026-09-19 18:44:20.505349
2026-09-19 18:25:00.000000	Lake George - Tower Road 138 kV l/o Lake George - Babcock 345 kV	Thermal	BASE	-237.85	2026-09-19 18:44:20.505349
2026-09-19 18:25:00.000000	ELIMSPOR-SUNBURY B 230 KV	Thermal	LINE 230 KV MONTOUR-SAEGERS MON-SAE;MONTOUR 230 KV MONTOUR MILTSAE1 CB;MONTOUR 230 KV MONTOUR SAEG1 CB;SAEGERS 230 KV SAEGERS CLN_MON CB;SAEGERS 230 KV SAEGERS MONT_1 CB;	-3.83	2026-09-19 18:44:20.505349
2026-09-19 18:25:00.000000	CONASTON-OTTCRKPL 2302 B 230 KV	Thermal	CONASTON 500 KV CONASTON 5012/500-4 GCB B;CONASTON 500 KV CONASTON 5012/3-500B GCB C;LINE 500 KV CONASTON-PEACHBOT 5012;PEACHBOT 500 KV PEACHBOT 235 CB;PEACHBOT 500 KV PEACHBOT 245 CB;	-211.09	2026-09-19 18:44:20.505349
2026-09-19 18:25:00.000000	NOTTINGHM 1-3 SER DEV A 230 KV	Thermal	CONASTON 500 KV CONASTON 5012/500-4 GCB B;CONASTON 500 KV CONASTON 5012/3-500B GCB C;LINE 500 KV CONASTON-PEACHBOT 5012;PEACHBOT 500 KV PEACHBOT 235 CB;PEACHBOT 500 KV PEACHBOT 245 CB;	-237.6	2026-09-19 18:39:21.036596
2026-09-19 18:25:00.000000	Lake George - Tower Road 138 kV l/o Lake George - Babcock 345 kV	Thermal	BASE	-237.85	2026-09-19 18:39:21.036596
2026-09-19 18:25:00.000000	ELIMSPOR-SUNBURY B 230 KV	Thermal	LINE 230 KV MONTOUR-SAEGERS MON-SAE;MONTOUR 230 KV MONTOUR MILTSAE1 CB;MONTOUR 230 KV MONTOUR SAEG1 CB;SAEGERS 230 KV SAEGERS CLN_MON CB;SAEGERS 230 KV SAEGERS MONT_1 CB;	-3.83	2026-09-19 18:39:21.036596
2026-09-19 18:25:00.000000	CONASTON-OTTCRKPL 2302 B 230 KV	Thermal	CONASTON 500 KV CONASTON 5012/500-4 GCB B;CONASTON 500 KV CONASTON 5012/3-500B GCB C;LINE 500 KV CONASTON-PEACHBOT 5012;PEACHBOT 500 KV PEACHBOT 235 CB;PEACHBOT 500 KV PEACHBOT 245 CB;	-211.09	2026-09-19 18:39:21.036596
2026-09-19 18:20:00.000000	ELIMSPOR-SUNBURY B 230 KV	Thermal	LINE 230 KV MONTOUR-SAEGERS MON-SAE;MONTOUR 230 KV MONTOUR MILTSAE1 CB;MONTOUR 230 KV MONTOUR SAEG1 CB;SAEGERS 230 KV SAEGERS CLN_MON CB;SAEGERS 230 KV SAEGERS MONT_1 CB;	-7.53	2026-09-19 18:44:20.505349
2026-09-19 18:20:00.000000	CONASTON-OTTCRKPL 2302 B 230 KV	Thermal	CONASTON 500 KV CONASTON 5012/500-4 GCB B;CONASTON 500 KV CONASTON 5012/3-500B GCB C;LINE 500 KV CONASTON-PEACHBOT 5012;PEACHBOT 500 KV PEACHBOT 235 CB;PEACHBOT 500 KV PEACHBOT 245 CB;	-254.89	2026-09-19 18:44:20.505349
2026-09-19 18:20:00.000000	ELIMSPOR-SUNBURY B 230 KV	Thermal	LINE 230 KV MONTOUR-SAEGERS MON-SAE;MONTOUR 230 KV MONTOUR MILTSAE1 CB;MONTOUR 230 KV MONTOUR SAEG1 CB;SAEGERS 230 KV SAEGERS CLN_MON CB;SAEGERS 230 KV SAEGERS MONT_1 CB;	-7.53	2026-09-19 18:39:22.074718
2026-09-19 18:20:00.000000	CONASTON-OTTCRKPL 2302 B 230 KV	Thermal	CONASTON 500 KV CONASTON 5012/500-4 GCB B;CONASTON 500 KV CONASTON 5012/3-500B GCB C;LINE 500 KV CONASTON-PEACHBOT 5012;PEACHBOT 500 KV PEACHBOT 235 CB;PEACHBOT 500 KV PEACHBOT 245 CB;	-254.89	2026-09-19 18:39:22.074718
2026-09-19 18:15:00.000000	NOTTINGHM 1-3 SER DEV A 230 KV	Thermal	CONASTON 500 KV CONASTON 5012/500-4 GCB B;CONASTON 500 KV CONASTON 5012/3-500B GCB C;LINE 500 KV CONASTON-PEACHBOT 5012;PEACHBOT 500 KV PEACHBOT 235 CB;PEACHBOT 500 KV PEACHBOT 245 CB;	-336.77	2026-09-19 18:44:20.505349
2026-09-19 18:15:00.000000	ELIMSPOR-SUNBURY B 230 KV	Thermal	LINE 230 KV MONTOUR-SAEGERS MON-SAE;MONTOUR 230 KV MONTOUR MILTSAE1 CB;MONTOUR 230 KV MONTOUR SAEG1 CB;SAEGERS 230 KV SAEGERS CLN_MON CB;SAEGERS 230 KV SAEGERS MONT_1 CB;	-16.25	2026-09-19 18:44:20.505349
2026-09-19 18:15:00.000000	CONASTON-OTTCRKPL 2302 B 230 KV	Thermal	CONASTON 500 KV CONASTON 5012/500-4 GCB B;CONASTON 500 KV CONASTON 5012/3-500B GCB C;LINE 500 KV CONASTON-PEACHBOT 5012;PEACHBOT 500 KV PEACHBOT 235 CB;PEACHBOT 500 KV PEACHBOT 245 CB;	-275.63	2026-09-19 18:44:20.505349

Coverage

100.0% complete0 gap days3 days with data

Show coverage history

Coverage: 100.0%Days with data: 3Gaps: 0

2026

gaplessmore

Related congestion & constraints data

Related congestion & constraints data
Dataset	Description
Constraint Shift Factor RunsPJM · nightly (one row per completed run)	One row per COMPLETED nightly estimation of PJM constraint shift factors, and the only record that a run finished. Resolve the latest usable run here — computed_at = (SELECT max(computed_at) FROM atg.pjm_constraint_sensitivity_runs) — and never off max(computed_at) of the sensitivities themselves, because a run writes its rows in blocks that all carry the new timestamp and an unfinished or abandoned run would otherwise look like the newest one. Each row also carries how much evidence that run had: interval_coverage is the fraction of published dispatch intervals that survived admission, intervals_refused_unexplained counts intervals showing congestion with no constraint recorded as binding (an unobserved binding set), constraint_feed_lag_minutes is how far the constraint feed trailed the price feed, and constraints_seen / constraints_in_fit / constraints_reported show how many constraints bound, how many were good enough to control for, and how many earned a published estimate.
Constraint Shift Factors (Estimated)PJM · nightly (60-day rolling estimation window)	Estimated sensitivity of every PJM pricing location's price to every binding transmission constraint: one row per constraint, contingency, and location, recomputed nightly over a rolling 60-day window. This is what answers 'which nodes drive this constraint' and 'which constraints is this node exposed to'. THE DAY-AHEAD MARKET, not real time: this estimate is fitted to day-ahead marginal values against day-ahead nodal congestion and it describes day-ahead congestion. It covers PJM's day-ahead binding constraints with their contingency over roughly 14,450 pricing nodes. PJM names no terminals, so from_station and to_station are always empty. PJM's real-time shadow prices ARE ingested now (pjm_rt_marginal_value, pjm_transmission_limits) but no estimate has been fitted to them and no atg.pjm_constraints_rt canonical table exists yet — a real-time PJM answer needs that fitting work, not a new ingest. shift_factor is in the ISO's orientation — POSITIVE means an incremental MW injected at that node increases loading on the constraint and the node is paid below system lambda while it binds; NEGATIVE means generation there relieves the constraint and earns a premium. These are ESTIMATES recovered from the price identity LMP = energy - sum(shift_factor x shadow_price), not a published PTDF matrix. They are measured RELATIVE TO THE MARKET'S REFERENCE — the identity yields SF(node) - SF(reference), so a single absolute value should be quoted as 'relative to the system reference' rather than as the node's PTDF, while DIFFERENCES between nodes are exact because the reference term cancels. Three further differences from a published matrix: they describe a NODE (a generator at that node inherits its location's value, and two units at one node are indistinguishable), they reflect the topology actually in effect across the window including outages rather than a stated base case, and every one carries a std_error from a 200-draw block bootstrap that resamples whole days. Read std_error before quoting shift_factor: an estimate whose absolute value is not at least twice its standard error is not distinguishable from zero. estimation_status says why a row has no number — 'thin_support' (in the fit, so it is controlled for, but under 12 binding intervals or under 3 distinct binding days), 'no_support' (under 3 binding intervals; not a regressor), or 'collinear' (it bound in lockstep with another constraint, so the two cannot be separated). Where from_station and to_station are populated they identify the monitored element and are NOT the constrained direction — the sign of shift_factor is what says which way. Every read must pin computed_at to one run, and must resolve that run through the companion atg.<iso>_constraint_sensitivity_runs ledger rather than off max(computed_at) here — rows are written in blocks that all carry the new timestamp, so an unfinished or abandoned run would otherwise look like the newest. Mixing runs averages a node across different network topologies.
Day-Ahead Constraint Marginal ValuesPJM · hourly (day-ahead)	What each binding day-ahead transmission constraint cost in PJM, hour by hour: the monitored facility, the contingency facility, and the constraint's marginal value — its shadow price, the saving from one more MW of headroom. This is the table that says how hard a constraint bound, where pjm_da_transconstraints says only that it did. PJM PUBLISHES THIS VALUE AS A NEGATIVE NUMBER: 2,654,985 negative rows against 43 positive over the table's full history, which reaches back to 2010. Read its magnitude as the cost of the constraint and do not compare its sign against another market's. This answers day-ahead congestion only; for real-time, see pjm_transmission_limits and pjm_rt_marginal_value. Source: PJM Market Data.
Day-Ahead Transmission ConstraintsPJM · daily (day-ahead)	The transmission constraints that bound in PJM's day-ahead market: the monitored facility, the contingency facility, the duration, and the congestion event. It names which elements are expected to limit flows for the next operating day. What it does not carry is what the constraint COST: the marginal value is published separately, in pjm_da_marginal_value. For real-time binding constraints, see pjm_transmission_limits (the live tip, ~9 minutes behind) and pjm_rt_marginal_value (the settled record, ~20 hours behind). Source: PJM Market Data.