OSM Ground Mounted Recloser Kiosk Help Protects, Controls & Automate Underground Smart Grid

Online, May 25, 2010 (Newswire.com) - The OSM automatic circuit recloser has been extensively type tested by independent laboratories to ensure long life and reliability under the harshest environmental conditions. It is the only solid di-electric insulated recloser to provide controlled arc fault venting and independent testing provides verification of this important safety feature.

The RC controller provides all the protection, data logging and communications functions. An operator panel is used to operate the device locally.

A two phase VT located in the main compartment provides low voltage AC auxiliary supply to the RC controller.

A manual trip mechanism is located above the RC controller, and is used to manually open and isolate the OSM. The mechanism is then rotated using a lever to connect earth switches to the Load side of the OSM.

Underground cables enter the kiosk through a metal plate provided in the base of the cable connection compartment. Six DIN 400 or ANSI Taper aromatic epoxy bushings are provided to terminate the cables onto the Load and Source side of the OSM automatic circuit recloser. An earth bar is also located in this compartment for earth bond connections.

The kiosk is manufactured from stainless steel or zinc anneal and is powder coated. The control compartment is protected to IP 65 / NEMA 4, while the main compartment and cable connection compartment are both protected to IP55 / NEMA 3.

The kiosk is mounted on a hot-dip galvanised plinth base. Two lifting points are provided on the top of the kiosk at either end. The plinth has two sling guides underneath so the kiosk can be lifted in a safe manner.

The OSM automatic circuit reclosers incorporate vacuum interrupters inside a solid dielectric polymer housing enclosed inside an arc vented stainless steel tank. This ensures the maximum in life and reliability with a fully insulated arrangement inside the long life housing.

Voltage is measured on all six (6) bushings using capacitively coupled conductive rubber screens. Current is measured on all six (6) bushings using Rogowski sensors. Three (3) bushings provide phase current measurements and the other three (3) bushings provide residual current measurement.

The recloser mechanism is operated by three (3) separate magnetic actuators, one per phase. These magnetic actuators are mechanically interlocked to guarantee correct three (3) phase operation. The device is latched in the closed position by magnetic latching. Each magnetic actuator uses a single coil and are the result of fourth generation development of magnetic actuators using remanence latching.

The open and closed position of the device is indicated by a green '0' to indicate the device is open and a red 'I' to indicate the device is closed, this can be viewed through the window next to the control cubicle.

The status of the recloser is also reflected by a microswitch connected to the control electronics. The electronic circuit board where the microswitch is fitted has no active elements which dramatically improves impulse immunity.

The main circuit bushings are manufactured from UV stable polymer and have a silicone rubber bushing boot to provide the required creepage distance.

The magnetic actuators are operated from stored energy charged capacitors located in the RC control cubicle. There is a rating plate located in the base of the tank that provides tank rating details in accordance with the requirements of ANSI C37.60.