User's Guide

Table Of Contents

D000587 SmartBypass User Guide

Revision A

5 Electrical Operation of Single Module

The SmartBypass comes in several different models as shown in Table 2. The SmartBypass can operate at line

currents of thousands of amps during normal bypass operation and withstand different fault current levels

depending on the model. The SmartBypass models are differentiated by continuous current rating and maximum

fault current rating. For example, the SmartBypass 4000-63 is rated for continuous line currents up to 4000 A RMS

and fault currents of up to 63 kA RMS for 1 second.

The SmartBypass provides telemetry when operating in monitoring mode or injection mode. The SmartBypass

operates to protect the power electronic components within Smart Wires series compensation devices by

operating when the devices are switched in series with the line, when a fault occurs on the line and when the

devices are switched out of series with the line. The SmartBypass can bypass Smart Wires series compensation

devices within in 1 msec of the inception of a fault, thus ensuring the protection of internal power electronics of

the devices. Figure 5-1 illustrates the basic electrical configuration of the SmartBypass.

5.1 Enclosure

The enclosure of the SmartBypass is connected to the transmission line at one terminal, this ensures the enclosure

is at line potential. All other terminals and components are insulated from the enclosure.

5.2 Inductors

Each SmartBypass contains two small inductors, represented by L1 and L2, one on either side of the normally

closed vacuum series link, S1. The inductors ensure the voltage across S1 is close to 0 V when S1 opens and closes,

extending the lifetime of this component.

5.3 Normally Closed (NC) Contactor

The normally closed contactor, represented by S1-NC, carries the current when the Smart Wires series

compensation devices are bypassed under normal conditions. S1 is what determines the continuous current rating

of the SmartBypass, S1 can carry either 2000 A RMS continuously or 4000 A RMS continuously.

5.4 Silicon Controlled Rectifiers

Each SmartBypass contains one or more pairs of anti-parallel silicon-controlled rectifier (SCR), shown as S2 in figure

2. The SCRs carry the line current in the case of a fault or when S1 operates to switch in or switch out the Smart

Wires series compensation devices.

5.5 Metal Oxide Varistor

The SmartBypass is equipped with a metal oxide varistor, MOV1 in Figure5-1. MOV1 protects the internal

components of the SmartBypass from high current events such as lightning strikes.