Ge-industrial-solutions AKD-8 Manuel d'utilisateur télécharger pdf

TYPE AKD-8

Low-Voltage Switchgear

_____________________________________________

High Resistance Pulsing Ground Detection

System

GENERAL

Pulsing Current High Resistance Neutral Grounding

System

The following paragraphs describe a high resistance neutral

grounding system supplied with GE AKD-8 Low voltage

Switchgear. The system features an alarm system and utilizes

a pulsing current to locate the first ground fault. The system

has the following basic features:

1. Grounds the neutral of an ungrounded 3-phase power

system, utilizing the "high resistance" method. This

allows the system to operate as an "ungrounded" system

but eliminates the danger of high transient over-voltage

during certain types of ground faults.

2. Gives an immediate warning when the first ground fault

occurs.

3. Provides a method for quickly locating and removing the

fault before another fault develops on another phase,

thereby preventing circuit outages due to double line to

ground faults.

Reference: The high resistance grounding method is fully

described in IEEE Transactions on Industry and

EQUIPMENT DESCRIPTION AND

GROUNDING SYSTEM OPERATION

During normal conditions, with no ground fault on the

system, no voltage appears across the system and no voltage

appears across the grounding resistors. (Refer to Fig. 1).

When a ground fault occurs, the resistors limit the ground

current to a low value, adjustable between 0.9 and 3.6

amperes.

The voltage appearing across the resistors will be sensed by

the voltage coil of the meter relay. Auxiliary contacts

General Applications, Vol. IGA- 1 No. 5, Sept./Oct. 1965

under High Resistance Grounding.

Fault Locating

The success of operating a high resistance grounded system

relies heavily on a dependable method of searching out the

ground fault location to allow the faulty system member to be

removed with the least delay.

The two important innovations introduced in this equipment

to take the uncertainty out of signal tracing include:

1. Use of repeating, cyclic, switching sequence by which the

tracer current can be rhythmically switched to a slightly

higher value. This gives unique character to the tracer

signal by which it can be distinguished from steady state

background noise.

2. Use of an extremely sensitive ground-fault-current

sensing transformer such that extraneous noise will be

ignored and only the current-carrying member which

passes through the window will be registered on the

meter.

of the meter relay, operated by the voltage coil, may be used

for remote indications and annunciation.

A green indicating light on the equipment indicates that

control voltage is available and that the system is normal.

When a fault develops, a red indicating light on the

equipment will remain lighted until the ground fault is

removed. If no remote annunciator is available to notify the

operator, an audible signal may be added to the equipment as

an option. A rotating red signal beacon may be used in noisy

or remote installations.

GEI-72116 Installation/Operation Instructions

1 2 3 4 5 6 7 8

Résumé du contenu

Page 1 - Low-Voltage Switchgear

ggTYPE AKD-8Low-Voltage Switchgear_____________________________________________High Resistance Pulsing Ground DetectionSystemGENERALPulsing Current Hi

Page 2 - GROUNDING SYSTEM OPERATION

EQUIPMENT DESCRIPTION ANDGROUNDING SYSTEM OPERATION(CONT.)To trace the ground fault, the operator turns the selectorswitch to the "pulse" po

Page 3

GROUNDING SYSTEM OPERATION(CONT.)Grounding ResistorsSince ground current is limited by the resistors, the lastsection must never be shorted out by the

Page 4

Figure 2 Typical High Resistance Pulsing Ground Detection Elementary4

Page 5 - TABLE 5.1

(Using Accepted Normal Values of SystemCapacitance Charging Current)High Resistance Pulsing Ground Detector480 Volt WYE1. Familiarize yourself with t

Page 6 - Current, 480 Volt WYE

Testing For System Capacitance ChargingCurrent, 480 Volt WYE WARNING: Testing for capacitance charging cur- rent requires that the entire system

Page 7 - Figure 3. Testing Schematic

6Figure 3. Testing Schematic7

Page 8 - General Electric Company

gGE Electrical Distribution & Control_____________________________________General Electric Company41 Woodford Ave., Plainville, CT 06062GEI 72116

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Ge-industrial-solutions AKD-8 Manuel d'utilisateur

Naviguer en ligne ou télécharger Manuel d'utilisateur pour Équipement Ge-industrial-solutions AKD-8. GE Industrial Solutions AKD-8 User Manual Manuel d'utilisatio

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