GENERAL INFORMATION

Hubbell underground arresters are gapless, metal oxide varistor (MOV) type surge arresters. They are designed to provide shielded, dead-front arrester protection for underground systems up through 35kV. Hubbell underground arresters limit over-voltages to acceptable levels, protecting equipment and extending life.

The critical values for underground arresters are the discharge voltage (IR) and the IEEE Std. 386 interface class. In general, the lower the discharge voltage, the better the protection margin. Hubbell underground arresters are nonfragmenting.

Hubbell underground arresters fully conform to the safe-failure mode per IEEE Std. C62.11. The standard requires that should the arrester blocks fail, they will not be ejected through the body or side wall of the housing. The MOV blocks should exit out the bottom, down and away from equipment and personnel.

Application:

Hubbell underground arresters are designed to mate with 200 amp loadbreak interfaces that conform to IEEE Std. 386 Fig 5 (15kV) or Fig 7 (25 / 35kV).

A Hubbell arrester installed at the end of a radial system or at both ends of an open point in a loop circuit will provide excellent protection against high voltage surges resulting from lightning or switching. When combined with an Ohio Brass PVR (Riser Pole) arrester, optimum protection can be achieved.

Hubbell underground arresters are fully shielded and submersible, either continuously or intermittently, to a depth of 6 feet (2m).

Installation:

The Hubbell underground arrester should be installed utilizing a shotgun type hotstick.

Performance Characteristics:

Tests were performed in accordance with applicable sections of IEEE Std. C62.11 (Metal Oxide Surge Arresters for Alternating Current Power Circuits) with test levels chosen that represent typical underground distribution systems.

COMMON TERMS:

Discharge Voltage: The voltage the arrester develops while discharging a surge to ground. The lower the voltage, the better the protection

MCOV: Maximum Continuous Operating Voltage

MOV: Metal Oxide Varistors

TOV: Temporary Over-Voltage

Thermal Runaway: Arrester fails due to excess heat causing the arrester to conduct too much current

PRODUCT FEATURES:

Pulling Eye provides positive hotstick operation. The pulling eye strength exceeds 500 lbs of force.

Insulation consists of peroxide-cured EPDM rubber that offers proven, uncompromised reliability and dimensional stability.

Molded Shield of conductive peroxide-cured EPDM rubber meets all requirements of IEEE Std. 592 for exposed semi-conducting shields.

Drain Wire Tab provides a contact point to attach a #14 ground wire to ensure the shield is at ground potential and maintains deadfront construction.

Fiberglass Wrap ensures that the MOV block stack remains in one piece and prevents the blocks from breaching the side wall should the arrester fail.

ID Band provides clear visual identification of arrester MCOV and duty cycle ratings.

Flexible Lead is #4 AWG copper rope lay conductor 595 strand (7 x 85). Ends are soldered to prevent fraying. Standard length is 36" long. Other lead lengths are available.

MOV Blocks are the same ones found in Ohio Brass overhead arresters.

Hubbell Underground Arrester Selection

Selection of the arrester size is based upon the maximum continuous operating voltage (MCOV) line-toground that is applied across the arrester in service. For arresters on effectively grounded systems, this is normally the maximum line-to-ground voltage - e.g., 7.65kV on a 12.47kV multi-grounded system.

For ungrounded or impedance-grounded systems, the MCOV should be at least 90 percent of maximum phase-to-phase voltage. Smaller arresters than shown may be used; contact your Hubbell Power Systems account representative for details.