Category Archives for Ask Chris

A New Power Line Carrier Book is Now Available at www.plcexperts.net

Jeffrey Brown reached out to help announce his new book, Power Line Carriers – Simplified: A Field Engineer’s Perspective I don’t know much about power line carrier. I’ve only

High Impedance Busbar Differential Protection

We covered the basic operating principles of high impedance busbar differential protection in our previous post, I Want to Know How a High Impedance Differential Scheme Works. You should read that post

I Want to Know How a High Impedance Differential Scheme Works

We received this question from the Ask Chris form at relaytraining.com. Follow this link to ask your own question and it might appear in a future blog post. High Impedance Differential Scheme Testing High

What is DC Offset? Ask Chris

I was recently asked about DC Offset during a paper I presented at the 2015 Hands-On Relay School and struggled with an answer because I know what it looks like and I know it exists, but I’ve never heard

Ask Chris: What is the best path for high voltage electrical employment as a relay technician?

Here is a question submitted to the Ask Chris section of the RelayTraining.com website about the best path for electrical employment. I have just recently completed an IBEW apprenticeship and tested out

Please Explain the Principle of Weak InFeed Echo Permissive Over Reach Transfer Trip Schemes?

Rahim submitted this question to the Ask Chris section of the RelayTraining.com website. Most line distance protection schemes assume that the system will always be able to supply enough amps to make the

When I test induction disc relay type … Is the pickup value the value at which the disc starts rotating?

This question was submitted via the Ask Chris form where you can ask me relay testing questions that I can hopefully answer. Creating test plans for digital relays is often difficult because you can have

Testing Directional Overcurrent Relays

In the previous post about Directional Overcurrent relay (67) testing (Finding the Direction in Directional Overcurrent Relays), we reviewed Directional Overcurrent protection from a system perspective

Ask Chris: What is the difference between contactors, motor starters, relays and circuit breakers?

A reader submitted a question through the Ask Chris form. I’ve expanded the original question from “what are the differences between relays, contactors and motor starters?” to “What

CT Primary Injection Ratio Testing Problems

Situation after CT Primary Injection: New 230kv breaker Testing CT’s, 4000/5, by high current injection injecting 80 amps A phase to ground the secondary leads are shorted in a junction box A-B-C-N

Finding the Direction in Directional Overcurrent Relays

A reader recently asked a question about the forward and reverse directions described in the Directional Overcurrent Relay section of The Relay Testing Handbook series. I used electro-mechanical directional

SEL-321 Out-of Step Protection Problem?

SEL 321 OSB upper tests fine, lower is no-op but 51g comes in any ideas? I’m oversight on a project, test company is using a Doble 6150 w/ RTS, I’m not very familair with RTS sdg

SEL Test Procedure Negative-Sequence Volt-Pol Directional Overcurrent Element

I am writing to enquire about 67N test procedures, specifically Schweitzer relays. The Page 94 of the Relay Testing Handbook #C2 : Practical Relay Testing (50/51/67/59/27/81/87/21) by Chris Werstiuk says

ASEA RAGEA 27N Gen Neutral Undervoltage

I can not find up dated information on this relay. I am testing with a manta 5000. I put 60 vac 60 hz on leads 7 and 8 and the relay picks up. Then on lead 11 & 12 I put 180 Hz and bring up vac to

SBF-1 Westinghouse Breaker Failure Relay Failure Question

To all, We had a SBF-1 Breaker Failure Relay fail on us yesterday. The time delay was not working properly. We have many of these relays on our system and wanted to see if there has been a Relay Advisory,

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