Pad-mounted MOST fluid-filled switch

Modular design

Up to 6 ways of switches or fuses

FLuid-insulated, sealed design

Less intrusive than comparable designs

Deadfront construction

Minimizes high voltage safety hazards

Core features

Simple, economical approach to underground switching
Up to 6 ways of switches or fuses to meet specific requirements without the added cost of custom construction
High level of safety for both the operator and the general public with its deadfront design
Compact, low-profile unit that is considerably less obtrusive than comparable air-insulated designs

Fluid insulation provides for a compact, low-profile unit

Fluid insulation results in a considerably less obtrusive unit than comparable air-insulated designs. Insulating fluid also reduces maintenance and eliminates moisture, dirt and wildlife problems.

FR3 dielectric fluid

Ideal for utility, commercial and industrial applications

The wide selection of fuses available with the MOST fluid-filled switch make it easily adaptable to standardized distribution systems, and fits the majority of standard pads. The ELSG full-range current-limiting fuse provides consistent clearing of low currents as well as reliable high-speed interruption of high-magnitude short circuit currents. In addition to providing excellent protective characteristics over a wide range of applications, the “E” rated ELSG fuses have time–current characteristics that coordinate easily with other upstream and downstream protective devices.

ELSG full-range current-limiting fuse

Quicker and easier operation

Switched ways are available in four different positions: two-position open/close, four-position selector blade, four-position “V” blade and four-position “T” blade. Eaton’s “V” and “T” blade designs are unique in that they perform the function of three separate open/close switches. All switch operations are indicated on a single switch handle. Combining multiple functions on one switch not only permits quicker and easier operation but, in addition, makes possible a more compact unit.

MOST switch catalog

Operate in areas subject to moisture, flooding and snow

The deadfront, non-ventilated, tamper-resistant construction of low-profile MOST switchgear makes it suitable for operation in areas subject to excessive moisture, occasional flooding, and blowing snow. Additional sealing is provided by the Buna-N rubber gasket in the bolted cover. A full stainless steel construction option is available.

Specifications

Ratings

Normal voltage	15 kV	25 kV	35 kV
Maximum design voltage	15.5	27	38
BIL, kV	95	125	150
1-minute withstand (60 Hz), switch* and terminators, kV	35	60	70
Continuous current, amps (max.)	600	300	200**
Load switching, A	600	300	200**
Momentary current 10 cycles, A (asym.)	16,000	16,000	16,000
2 sec., A (sym)	10,000	10,000	10,000
3 shot make and latch A (asym.)	16,000	16,000	16,000
* The withstand rating of the switch is higher than that of the connectors (IEEE Std C37.74-2003 standard).
** An alternate two-position OPEN-CLOSE switch is available for 15 kV, 25 kV and 35 kV designs that have a 300 A continuous and load switching rating. This alternate switch meets IEEE Std C37.74-2003 standard requirements.

Fuses

ELSG kV	Description	MOST rating-kV
8.3	E rated, full-range current-limiting rating: 4, 8, 12, 15, 20, 25, 30, 40, 50, 60, 65, 80, 100 or 125 A	15
15.5	E rated, full-range current-limiting rating: 4, 8, 12, 15, 20, 25, 30, 40, 50, 60, 65, 80 or 100 A	25
23.0	E rated, full-range current-limiting rating: 4, 8, 12, 15, 20, 25, 30, 40, 50, 65, 80 or 100 A	25 and 35
23.0	Equivalent to A.B. Chance fuse SL54: 50 A SL90: 90 A	25 and 35

Accessories

1/2" copper ground rod (in lieu of ANSI standard stainless steel ground points)
1" drain valve with 3/8" sampler (in lieu of standard 1" drain plug and 3/8" sampler)
Fault indicator provisions, Qty. 6, located in the source or tap compartment sill
- Source compartment
- Tap compartment
304L stainless steel construction (in lieu of standard mild steel construction)
Spare-fuse storage rack
T-Handle (for manual switch options)
Fuse drip tray

Download Links

Catalogs

MOST oil switch catalog

This catalog describes ratings and ordering information for Eaton’s Cooper Power series MOST pad-mounted switchgear which offers the inherent advantages of pad-mounted apparatus for underground switching and modular design and provides a wide selection of switching combinations to meet specific requirements without the added cost of custom construction.

(PDF 1 MB , 10/01/2015)

Installation instructions

MOST fluid-filled switchgear instructions

This document describes installation instructions, operation information, testing instructions and maintenance procedures for Eaton’s Cooper Power series MOST fluid-insulated underground distribution switchgear.

(PDF 660 KB , 04/01/2018)

Product notifications

Eaton's Cooper Power series padmount switchgear maintenance advisory

This notice pertains to Cooper Power series fluid-filled type MOST, RVAC, VFI and PST family switchgear.

(PDF 453 KB , 05/02/2019)
Eaton's Cooper Power series padmount switchgear maintenance advisory (Canadian-French)

This notice pertains to Cooper Power series fluid-filled type MOST, RVAC, VFI and PST family switchgear.

(PDF 710 KB , 10/17/2019)

Product specification guides

Functional Specification for 15 kV, 25 kV, or 35 kV Underground Distribution Switchgear

This specification covers 15 kV, 25kV or 35 kV MOST underground distribution switchgear.

(DOC 901 KB , 06/01/2017)
MOST oil-insulated switchgear product specification product specification (PDF)

This specification covers 15 kV, 25kV or 35 kV MOST underground distribution switchgear.

(PDF 591 KB , 06/01/2017)

Service and troubleshooting

Field service instructions: Replacement of cover gasket for padmount switchgear side-hinge-2 models

This document provides field service instructions for replacement of cover gasket for Eaton's Cooper Power series padmount switchgear side-hinge-2 models.

(PDF 1 MB , 04/01/2019)

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Contact and process information

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800-497-5953 or 414-768-8205 or 414-768-8208

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