Siemens 480V manual Main and Ground Bus, Control Wiring, Insulation, Circuit Breaker Compartments

480V Metal-Enclosed Switchgear

Construction Details

General

4

Main and Ground Bus

The standard main bus is silver-plated copper. Welded aluminum is also avail- able. Provisions for future extension of aluminum main bus conductors include tin plated joints with high tensile strength steel hardware. Tin-plated copper bus is optionally available.

The main three-phase horizontal bus is arranged vertically one phase above the other with edge-to-edge alignment to provide high, short circuit strength. Insulated main and vertical bus are optional.

Main bus ratings available are 1600, 2000, 3200, 4000, or 5000 amperes con- tinuous current. A neutral bus is fur- nished when specified, and can be rated 1600, 2000, 3200, 4000 or 5000 amperes continuous current.

A standard copper ground bus extends through all sections. A cable lug can be mounted to the ground bus in each section.

Minimum bus bracing is 65,000 amperes RMS symmetrical. Higher symmetrical bracings are available based on the low- est breaker short circuit rating in the group.

Load side runbacks for feeder circuits are one-piece copper construction, are insu- lated with sleeve tubing in the main bus area, and are supported by high-strength, glass polyester moldings.

Control Wiring

Standard secondary and control wiring is #14 AWG extra-flexible, stranded copper type SIS. Terminations are made with compression-type, insulated terminals.

For devices not having screw-type termi- nals, tab-type disconnects are used.

Insulation

The insulation used is Pyro-Shield, a fiber- glass-reinforced polyester material that has high impact strength and low mois- ture absorption. Other features include high flame retardance, high resistance to chemical fumes, and long life at high temperatures.

Circuit Breaker Compartments

Typical circuit breaker compartments include primary disconnects, ground dis- connect, drawout rails, and associated interlocks, and secondary disconnects, if appropriate. Telescoping drawout rails allow the breaker to be withdrawn from the compartment without additional extensions or adapters. Compartments for electrically-operated circuit breakers include secondary disconnects and con- trol circuit fuses. Up to three current transformers for metering or relaying can be mounted in each compartment.

Circuit breaker compartment front panels can be used to hold a variety of auxiliary devices such as breaker control switch- es, ammeters, and test blocks.

480V Enclosed-MetalSwitchgear

a	Control Circuit Fuses	f	TOC Switch Operator
b	Ground Disconnect	g	Interference Interlock
c	Secondary Disconnect	h	MOC Switch Operator
d	Front Panel Devices	i	Space Heater
e	Primary Disconnect	j	Drawout Rails

Circuit Breaker Cell Interior

52	Siemens Electrical Products and Systems	CSI Section 16470
	Specification Guide