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Hello, I believe IEEE 519 is the way to go. However, nothing prevents you from correcting the harmonics content "nearer" to your source of harmonics. Take the example of a MV PCC (25kV) with a MV substation transformer 25/4.16kV and a LV substation transformer 4.16/0.6kV. If your source of...

Thank you jraef, that is exactly the kind of product I was searching for to add on the contact when you see old breakers that seem to have a tulip system that looks like it has no more lubricant on it.

You can definitely implement genset protections into a PLC (temperature, oil level, etc.) to initiate a trip of the main breaker. The PLC could send an input to an electrical protection relay managing the main breaker. But electrical protections need to be implemented using approved protection...

Thanks for the input. I was more looking towards the breaker electrical racking connections to the equipment bus bars though. If you have any idea for that one, it would be appreciated.

Hello, I cannot identify a grease that would be good for breaker connections to switchgear busbars in 600V and 15kV equipment. Am I asking myself too many questions and a simple good quality dielectric grease from an auto part do the job or if there are specific product for that. I know for...

For everyone's interest (who are interested on the subject). SEL wrote to me to keep any ferroresonance protection if there was any as the relay does not prevent it in any way.

Sure, here it is.

This comes from a Schneider Cahier Technique. The exemple in figure 11 is exactly how its done in the panel I am working on. The cahier technique even has explanations on how this setup prevents or damps the phenomenon of ferroresonance. However, I understand the setup at figure 12 is said...

Hi Waross, Sorry if my question isn't clear. My question is mainly: Should I keep the resistor previously installed in parallel of the PTs secondary when replacing the old electromechanical relays by the new SEL-751 relay. Can the SEL-751 relay prevent the ferroresonance phenomenon? Thanks! Coco

Yeah, thanks for you input. I will see if other people have different view of this. But, in SEL-751 instruction manual, I found zero mention of the word "resistor" in regards to PT connection and the word "ferroresonance" isn't mentioned once. I am starting to be convinced that those resistors...

Hello, I am working on modifications onto an old protection panel. There are 80 ohms resistors in parallel (Y-G) of the Y-G / Y-G PTs secondary on each phase (primary is 3ph/3wire 25kV and directly connected to the utility). This is mentioned as ferroresonnance protection and it makes sense...

Personnaly, i always exclude the main unless the equipment is arc-rated as it was mentioned above. To me, added insulating barriers is not enough. If the fault occurs upstream of your main device, but inside your equipment, what tells you that you will not receive the blast in the face? Even if...

Hello, I tried to search Google for this answer, but I always end up falling on websites explaining either how grounding works or why grounding is important... But, my question is the following: What methods are good to ground a junction box housing splices for multiple 480V feeders in the...

Gr8blu: Thank you for your input and providing less than 2kV cable application. With a little under 10 years experience, i haven't touched too many installations with DC motors. All i have seen is AC motors with VFDs nowadays :) But, my main question in this topic was to clarify when we can...

My memory was wrong yesterday. I did have different labels on all buckets 1 or 2 times. But,it was because I had some clients that their internal standards were to show the load end arc flash value on each specific bucket. Not saying it is the best practice, but that is how they wanted it. Those...

Hi Waross, Yes, i did notice it. But, digging hard yesterday i think i answered myself. And i honestly think that CSA 2kV DLO cannot be used at 2kV in permanent installations, but only in portable installations in Canada. I found article 4-040 that appears to be very clear that a DLO cable can...

Based on my little experience, for example an MCC, when buckets have breakers, it is more expensive than when they have fuses. That can also be taken into consideration in the design.

I did notice that Table 11 in the Code with a 2000V specification. Last version of the Code mentions the same thing. But, that Table 11 is for "Portable" installation. I am not sure i can apply it for a Tray or Conduit or Other permanent installation. Actually, I am kind of the consultant...

Are you talking about DC vs AC power or DC vs AC controls? For MCC, i often see AC controls (from control transformers) so in a loss of power or short-circuit with an upstream protection operating, the motors shut down immediatly and it is fail safe. I have often seen DC controls in switchgear...

Hello, I have a question about DLO insulation Rating. I always used them before into 600V distribution. So i never cared about the insulation rating of 1000V vs 2000V. But, into an installation, the 2kV insulation rating is required, but this is not a typical rated voltage for cables in...