Life expectancy of microprocessor-based protective relays (IED) 4

[oldfieldguy]

The question has arisen at my workplace as to what we expect out of these things. I have devices installed in excess of twenty years ago.

What do I tell our managers about their life expectancy? We're starting to see sporadic failures on devices.

That is not to mention that software, firmware and hardware revisions have passed up my installed devices long ago. My employer replaces laptop computers at five years. What am I supposed to believe about IED's that protect the plant power system that have been in service twenty years?

What's the industry consensus?

old field guy

 

[RRaghunath]

Below is from a paper by PSRC on end of useful life estimation:
Quote "The IEC describes useful life as “the time interval beginning at a given moment in time, and ending when the failure intensity becomes unacceptable or when the item is considered to be unrepairable as a result of a fault (IEV 191‐19‐06) [1].” Therefore, according to this definition the end‐of‐life is when the failure intensity becomes unacceptable or when the [recovery/repair] time is considered to be unacceptable as a result of a fault. Some examples for end of life include the loss of life of capacitors (loss of capacitance because of electrolyte drying and leakage), and loss of semiconductors (mainly ICs) that degrade because of thermal, vibration and humidity. The ability to determine the end‐of‐life will better prepare the utility for a successful asset management strategy as well as bolstering their rate case application." Unquote.
It seems not easy to give a figure like 20-years with the dynamics of technology and various factors involved in assessing the end of useful life for numerical relays.
Most of the vendors offer 10-years warranty and hence, what we can definitely say is 10-years as a minimum. Beyond that, every utility needs to evolve their own strategy it seems.
The above technical paper can be downloaded from

http://www.pes-psrc.org/Reports/I22-UsefulLife-Final-May2015a.pdf

 

Rompicherla Raghunath

 

[controlsdude]

I would create an upgrades group at your company. Start quoting upgrades and point out the manufacturers are starting to not support this product. This will generate fear in your customers which will generate upgrade projects. Which will generate a revenue stream for your company. Everyone wins and you can use your expertise in selecting a better product to support your customers with in future.

 

[HamburgerHelper]

Are you guys changing out the electrolytic capacitors? That is what fails on first gen microprocessor relays. At conferences this was pointed at as the week link. My former employer would change them out on ge relays.

Once the relays get that old, you probably want to change them out to match the system and stock in the warehouse.

 

[krisys]

If someone is buying the new relay or ordering the equipments containing the protection relays, it is better obtain the life cycle and obsolescence strategy from the relay vendor.

Sometimes, the offered generation of relays series may be at its final stages of obsoleting by the manufacturer. But, there may be some inventory left with them and they need to clear it out. So the relay vendor may give discount to the main equipment manufacturer. But the end user suffers due to this. If it is a long gestation project, before you commission, the relay vendor may tell you that now these relay series is obsolete even during the commissioning. Thus everything they supply (spares, service etc.) on that relay will be at premium for that relay.

It is like writing the obituary before the child is even born!

So to avoid this, the buyer should always ask the vendor to submit the obsolescence strategy showing in the bar chart, where the subject relays are located.

Normally, these are in four stages, like,
a) development & trial run stage (this is where lot of troubles coming in the product)
b) People should buy when the product is in the initial stage of stabilization of the product.
c) Matured stage (stabilized stage, where the relay is well established)
d) Phase out stage (where the manufacturer will be planning to develop a new series of product and planning to obsolete this series. One should not buy the product at this stage)
e) Obsolete, but manufacturer has not declared, and waiting to clear out his inventory (this is a very problematic area, where the un-suspecting customers fall to the trap!

 

[davidbeach]

The end user selects the relays. Anything else is madness.

 

[cranky108]

You always take a risk on anything you buy. You look at the company and evaluate the history and make a decision if this is a risk you can take.

If you have had poor results from buying from a company, and you keep buying from them because they are cheaper, or the salesperson takes you out for lunch, then you are foolish.

On the other hand, you should look at buying from two or more manufactures just so you know you have a backup source if your chosen company fails.
I sort of do this.

No we do not replace capacitors. We replace the whole device. The cost of having someone sit down and un-solder, and re-solder another one is more than a replacement or the failed devices.

 

[krisys]

obtaining the obsolescence strategy at least gives you a clue, what model not to buy, if the offered model is already in its later stage of matured stage of the product.

This approach will protect you (sort of an assurance) to some extent. You must request this from the vendor during the bidding stage itself.

I am not talking here only for the protection relays. This is also applicable for few other systems, like PLC systems, PMS/ECMS, switchgears etc.

May be not that relevant when it comes to totally custom deigned equipments, such as transformers, distribution boards etc.