Posts Tagged ‘fault current’

Impact of Current Transformers errors on protective relays

January 23rd, 2019 | Make a comment | Posted in Electrical Safety
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Picture 1. Bus through-fault currents

Picture 1. Bus through-fault currents

 

Current transformers are the interconnection element between the power system and all measurement devices like protective relays. CTs actually lower the value of the primary current to a nominal secondary level in order to be used by meters, protective relays, meters, and monitoring devices.

Here’s a list of the impacts of current Transformers errors on protective relays written by Electrical Engineer Mile.

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Ground rod: bad experiences

October 17th, 2016 | 1 Comment | Posted in Electrical distribution
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megaphone-redThis week, a fellow electrical engineer previously working in the industry (but since a couple of months more dedicated to academics/teaching) sent us an article.

His name is Pablo, and he wants to tell you his bad experiences concerning grounding.

Share your experiences too, send us a mail!

“Throughout my experience in housing construction as well as in the installation of raceways in existing buildings I have met with incorrect definitions concerning grounding with ground rods.

Among the myths that I have heard from technicians and customers I can mention:
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How to select a sectionalizer

February 12th, 2016 | 1 Comment | Posted in Electrical Safety
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Last day, A.N. one of our contributors told us how to select an Automatic Transfer Switch (ATS). Now, here he’s back to give us some knowledge about selecting a selectionizer.

If one of you want to share knowledge with the community to keep it alive, just send us a mail!

Introduction

Sectionizers are protective devices that are used in medium voltage distribution systems to automatically isolate faulted sections once an upstream recloser or breaker has interrupted the fault current. The self contained protective devices are usually installed downstream of a recloser in the distribution circuit.

The Sectionizers do not have the capacity to break the fault current and are usually used in conjunction with other backup devices such as reclosers and circuit breakers that have the ability of breaking the fault current. When in operation, the sectionalizer counts the number of interruptions occurring on the circuit. It does this by monitoring the number of times the recloser opens.

Figure 1 : Typical sectionalizer connection

Figure 1 : Typical sectionalizer connection


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