Herlec
Switchgear Upgrades
Retrofit, Replacement or Refurbishment of Switchgear
When faced with ageing switchgear that no longer meet your requirements, you are normally faced with these three options : retrofit, replacement or refurbishment of that switchgear.
Herlec sub station
Switchgear
RCB15_HD1_BBC-275
CONSIDER THIS WHEN DECIDING TO RETROFIT, REPLACE OR REFURBISH AGING SWITCHGEAR
When faced with ageing switchgear that no longer meet your requirements, you are normally faced with these three options :
retrofit, replacement or refurbishment
of that switchgear.
The problems you may encounter are summarized below:
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SAFETY - Modern switchgear have evolved to a point where it is safer to operate than the old switchgear. The modern trend towards safety and user liability makes this an important criteria.
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OPERABILITY - Networks are becoming more and more automated. This may require technology far beyond the capability of the old switchgear.
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MAINTAINABILTY - Availability of skilled personnel may become a problem and prices might be exorbitant.
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AVAILIBILTY OF SPARES - Parts have a limited production life as technology improvements cause them to be superseded. Lack of spares normally result in malfunctions or equipment being beyond repair.
Once you have decided you are faced with 3 options:
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REPLACEMENT - The old switchgear is stripped out and completely replaced with new switchgear.
2. REFURBISHMENT - Here you retain the old switchgear and do an extensive overhaul. Critical parts may be replaced. The main feature is that the old switchgear is not modified.
3. RETROFITTING - Retrofitting is the replacement of certain parts of the switchgear. This could be only the circuit breaker, protection & control or certain current carrying parts, but keeping the basic structure or enclosure.
Advantages And Disadvantages:
With retrofits or refurbishment there arises some questions like – can the switchgear conform to certain specification such as , short circuit , BIL, ability to break faults etc.
There are four possibilities to overcome this problem - type test, extrapolation, calculation, approximation and synthesis:
a) Type Test
Here one manufactures a prototype and performs the relevant tests. There are limitations such as cost, time constraints, failure and rework and difficulty in obtaining the prototype.
It is only viable if you are retrofitting large quantities so that you can spread the cost.
b) Approximation & Extrapolation
If you have existing data on the circuit breaker that verifies its performance, you could extrapolate that data to the new installation if its important features are not changed eg.
Busbar sizes, contact arrangements and clearance.
One could then state with a degree of certainty that the retrofits performance would be met.
c) Synthesis
If each building block has to be tested individually and then when brought together, the final result could deemed acceptable by virtue of its components.
The uncertainty would be the interfacing, but this may be treated by extrapolation or calculation.
For example if the circuit breaker and the panel had been tested individually then you could say with a degree of certainty that the combination would meet the require performance.
d) Calculation
It could be possible to calculate whether equipment in a retrofit would be able to meet required performance.