Overview

Comking three-phase pad-mounted transformers is oil-filled, three-phase, commercial pad mounted distribution transformer specifically designed for outdoor installation on a concrete pad and provide underground power distribution to commercial, industrial and institutional loads. It is available in both live front and dead front construction, for radial feed and loop feed applications, with or without taps, the transformer uses aluminum or copper winding and is optimized to maximize efficiency and footprint. It has many advantages:such as high voltage, no drifting of neutral point, low loss, small volume, cost-effective, safety and environment protection and etc.

Standard

Three-phase pad-mounted transformer is designed and tested in accordance with industry standards including IEEE C57,  ANSI C57， IEC60076 as applicable.

Product Scope

With high voltages up to 40.5 kV and ratings up to 7500 kVA

Product Type

Radial Feed

Standard Features

? 50 Hz or 60 Hz operation.

? 65 oC average winding rise.

? Radial & loop feed arrangements.

? Dead and live front type of HV terminals.

? Bolted-on cabinet with removable sill having the following depths :

 - 19" deep for 300kVA through 750 kVA

 - 22" deep for 1000kVA through 1500kVA

 - 24" deep for 2000 kVA through 3750kVA

 - 30" deep for 5000 Kva through 7500kVA

? Tank : Mild steel

? Steel HV/LV compartment barrier

? Padlocking facility with penta-head bolt on the HV and LV, Three-point latching mechanism.

? HV and LV compartment doors-hinged and lift-off type with 120° holding bars

? Stainless steel door hinges

? Removable sill for easy installation

? Three-point latching door for security

? Permanent Nameplate per ANSI requirement.

? ANSI tank ground pads.

? One-inch drain valve and sampler.

? Self-actuating pressure relief valve.

? Four(4) lifting lugs

? Welded cover with hand hole

? Oil fill plug

? Removable LV neutral ground strap; as required

? Durable, corrosion-resistance powder coat paint finished Munsell Green 7GY3.29/1.5

? Designed,manufactured and tested in accordance with the latest ANSI and IEEE standards.

Optional Features & Accessories

? Specific customer applications and the new DOE efficiency requirements.

? Liquid level gauge

? Liquid temperature gauge

? pressure vacuum gauge

? Copper and aluminum windings available.

? Dual high-voltage ratings.

? Internal expulsion fuses.

? Current limiting fuses.

? Internal oil-immersed partial range current-limiting fuses.

? Bayonet fuse holders with and without flapper.

? Internal oil switch (radial or loop).

? Under oil internal arresters.

? Low-voltage molded-case circuit breaker.

? Special colors.

? Partial stainless steel design(cabinet sill and tank bottom) 

? 30”or 34”or 40”deep cabinet 

? CT's or PT's including mounting support 

? LV externally mounted molded case breaker 

? Externally mounted kWh meter 

? Flip-top cabinet for low profile design 

?  Additional externally mounted nameplate

Tests

Comking performs routine testing on each transformer manufactured including the following tests.

? Resistance tests of all windings. 

? Ratio tests on the rated voltage and all tap connections.

? Polarity and phase relation tests at rated voltage.

? No load loss at rated voltage.

? Exciting current at rated voltage.

? Impedance and load losses.

? Applied voltage test.

? Induced voltage test.

? Full-wave impulse test.

? Mechanical leak test.

Structural characteristics

Cores

Cores are manufactured with precision cut, burr-free, grain-oriented silicon steel. Many grades of core steel are available for optimizing core loss efficiency.

Coils

Pad-mounted transformers feature a rectangular coil configuration with wire-wound, high-voltage primaries and sheet-wound secondaries. The design minimizes axial stress developed by short circuits and provides for magnetic balancing of tap connections.

Coils are wound using the highest quality winding machines providing exacting tension control and conductor placement for superior short-circuit strength and maximum efficiency.

Core and coil assemblies

Pad-mounted transformer core and coil assemblies are braced with heavy steel ends to prevent the rectangular coil from distorting under short-circuit conditions. Plates are clamped in place using presses, and welded or bolted to form a solid core and coil assembly.

Tanks

transformer tanks are designed for high strength and ease of handling, installation, and maintenance. Tanks are welded using precision-cut, hot rolled, pickled and oiled steel.