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Underground Distribution Sensor

The SEL-8301 Underground Distribution Sensor is designed to optimize outage management and improve underground reliability. With a line current measurement accuracy of 1.5 percent, it allows for more effective switching decisions, letting you restore power to more customers. Using a wireless network, the SEL-8301 sends fault, load current, and water depth information to your control center for efficient dispatching of repair crews and reduced outage durations. The flexible design makes the SEL-8301 ideal for underground vaults, pad-mounted switchgear and transformers, and high-rise distribution feeders and transformer rooms. 

Starting At

$2,100 USD

This price is for a 3 phase system.

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Improve Underground Reliability—Reduce fault location time with the SEL-8301. Fault information and load data are sent via a wireless RPMA network to the central operations center for dispatching repair crew personnel. With accurate fault location, crews can focus on restoring power instead of patrolling lines.

Improve Operational Efficiency—Automatically measure and report the water level in a subsurface vault or manhole with the water depth sensor. The sensor enables the utility to accurately dispatch the right number of pump trucks to the vault. This ensures the vault is ready to enter upon repair crew arrival, reducing the time a repair crew is onsite.

Enhance Operator Decision Making—Sectionalize around the faulted cable section on feeders connected to medium-voltage pad-mounted switchgear and junction boxes. Take advantage of the accurate SEL-8301, which collects reliable load data by monitoring critical points on the distribution system to prevent cable overloading. This information helps operators make switching and sectionalizing decisions during emergency conditions.

Accurate Fault Determination—Determine the fault type and prioritize repair efforts to improve system reliability. The SEL-8301 automatically adapts its trip threshold based on the measured load current to ensure good coordination. It monitors for system protection operations to distinguish between fault types, circuit outages, and normal system conditions.

Reliability in Harsh Subsurface Environments—The SEL-8301, SEL-8302 Current Transformer, and various accessories exceed the demanding requirements of underground applications and are suitable for harsh subsurface vault applications susceptible to flooding. With IP68 ingress protection, the SEL-8301 reliably operates in water up to 15 feet (4.5 meters) deep.

Remote Monitoring—Eliminate the challenges of locating and troubleshooting for faults in hard-to-reach subsurface applications, such as manholes and vaults. Monitor electric distribution circuits in high-rise buildings and large factory facilities. Utility personnel no longer need to enter a vault or structure to locate the fault. All sensor statuses can be viewed remotely from a centralized display.


Current Measurement Accuracy±1.5 percent typical, ±4 percent specified
Current Measurement Range20–650 A
Water Depth Measurement Accuracy±0.5 in +1 percent of reading
(in cu. ft. and percentage of vault filled)
Ports12 sensor ports for current measurement and energy harvesting (supports up to 12 phases or 4 three-phase circuits)
NetworkRPMA network
Radio Operating Frequency2.4 GHz ISM band
Power Requirements 20 A per phase minimum with 3 SEL-8302 Current Transformers and with a 3-hour reporting-interval
Operating Conditions–40° to +80°C (–40° to +176°F)
Weight1.2 kg (2.7 lb)
MountingMounting tabs for screws
Optional magnetic mounts
WarrantyTen years, no questions asked


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