Span Sentry

Span Sentry

Dynamic Line Rating System

Span Sentry provides an accurate, real-time estimation of the ampacity (current carrying capacity) of transmission conductors for a maximum operating temperature.

Incorporating multiple on-site sensors, Span Sentry monitors conductor clearance, line current and weather conditions to calculate conductor ampacity, temperature and tension.

This summary information is provided in real-time to EMS operators in order to more efficiently manage their transmission network, particularly in high load and contingency situations.

WHY SPAN SENTRY

Span Sentry calculates ampacity by accurately measuring conductor sag, which is directly related to the intrinsic conductor temperature. Conductor sag and temperature result from the cumulative effects of heating and cooling variances over several spans of conductor. Single point measurements of conductor temperature are a less accurate means of accounting for the net impact of these multiple factors.

Span Sentry calculates and immediately communicates ampacity on SCADA or cellular Internet in real-time, without the need for installing additional hardware or software at a substation or operations center. Supporting data, such as ampacity based on live weather monitoring, conductor tension, and line current can also be provided. Live images of the monitored conductor can be provided separately over cellular internet.

Span Sentry can be installed in 4 hours (or less) on any system at any location without de-energizing lines, and can be easily removed and re-located to another location.


GRID WATCH FIELD DATA

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Pricing & Ordering

Samuel Jack  |  970-204-4001  |  This email address is being protected from spambots. You need JavaScript enabled to view it.
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Diane Hurst  |  970-204-4001  |  This email address is being protected from spambots. You need JavaScript enabled to view it.


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FAQ's

What does Span Sentry provide to an electric utility?

What does Span Sentry provide to an electric utility?

Span Sentry provides an accurate, real time estimation of the ampacity (current carrying capacity) of transmission systems for a maximum operating temperature. This information allows EMS operators to more quickly and efficiently manage their transmission network, especially in high load and contingency situations. This allows utilities to validate and/or modify their static ratings, avert forced outages, alleviate line constraints, and defer costly line up upgrades.

How does Span Sentry work?

How does Span Sentry work?

Span Sentry utilizes on-site sensory data collected on a span of overhead transmission conductor to furnish real-time ampacity information. The system employs a specialized machine vision camera to directly measure conductor clearance with a ± 0.5 in / 15mm accuracy level both vertically and horizontally – day or night. Weather sensors monitor wind speed and direction, ambient temperature and solar radiation. A current sensor monitors and reports line amperage to generate a complete snapshot of the load carrying capacity of a transmission circuit.

Why Span Sentry?

Why Span Sentry?

Span Sentry calculates ampacity by accurately measuring conductor sag, which is directly related to the intrinsic conductor temperature.  Conductor sag and temperature result from the cumulative effects of heating and cooling variances over several spans of conductor.   Single point measurements of conductor temperature are a less accurate means of accounting for the net impact of these multiple factors.

Span Sentry calculates and immediately communicates ampacity on SCADA or cellular Internet in real-time, without the need for installing additional hardware or software at a substation or operations center.  
Supporting data, such as ampacity based on live weather monitoring, conductor tension, and line current can also be provided.  Live images of the monitored conductor can be provided separately over cellular internet.

Span Sentry can be installed in 4 hours (or less) on any system at any location without de-energizing lines, and can be easily removed and re-located to another location.

What are Span Sentry’s installation requirements? Is installation assistance available?

What are Span Sentry’s installation requirements? Is installation assistance available?

Span Sentry has no installation limitations, and can be quickly deployed (usually 4 hours or less) on energized lines anywhere on a transmission system, on any type of structure. It can be just as easily removed and re-installed at another location within the same timeframes.

EDM provides on-site installation assistance upon request.

Can Span Sentry be configured to monitor more than one conductor?

Can Span Sentry be configured to monitor more than one conductor?

Yes. A single system can accept input from two cameras, providing simultaneous monitoring for adjacent spans.

How is Span Sentry Powered?

How is Span Sentry Powered?

Span Sentry uses a self-contained photovoltaic system to support operation virtually anywhere on a utility transmission circuit.

What type of communication options are available for Span Sentry?

What type of communication options are available for Span Sentry?

Span Sentry can be deployed using a variety of communication systems, including M2M - CDMA or GSM IP networks, local radio or fiber optic configurations.

What software options are available to support line rating analysis?

What software options are available to support line rating analysis?

EDM provides a real-time web based data service called GridWatchRT, available via any web browser over the Internet. Live ampacity data is received from Span Sentry, along with individual readings displaying clearance, temperature, wind speed/direction and line current.

What are Span Sentry’s calibration requirements?

What are Span Sentry’s calibration requirements?

If assisting with the installation, EDM will measure the ground-to-target clearance using a laser rangefinder. Then, using survey data and/or a PLS-CADD model of the span, EDM formulates a model of the span to generate a sag-temperature relationship. From there, 3-6 weeks of line current data provided by the utility will be used to verify the current sensor calibration. The system can then provide summary ampacity information.

What type of warranty comes with Span Sentry?

What type of warranty comes with Span Sentry?

A one year full service warranty is included, with annual extended warranties available.

How long has EDM been involved in Line Rating?

How long has EDM been involved in Line Rating?

EDM first performed line rating studies in the 1990s, in which probabilistic-based static ratings were derived from decades of weather data. In 1997 these studies inspired a joint development with the Electric Power Research Institute (EPRI) to design a line rating system based on conductor sag. The first prototype “Sagometers” were deployed on utility systems in 1999.  Since that time, over 80 units have been deployed throughout North America.

In 2012, EDM began developing its first dynamic line rating system incorporating elements of Sagometer to provide total circuit ampacity for transmission systems.

What happened to the Sagometer system?

What happened to the Sagometer system?

Span Sentry incorporates elements of the original Sagometer product that directly measures conductor sag using a camera and target system. This technology was developed in conjunction with EPRI and the California Energy Commission, and has been deployed throughout the US and Canada over the past several years. Complimenting Sagometer with advanced weather and current sensors, Span Sentry combines these sensory aspects to derive circuit ampacity.

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