In reality, transformer bushings, especially low voltage types, are among the least costly components required in transformers. At the same time they are extremely vital in their function and failures can result in drastic consequences.
It is therefore rather surprising that many manufacturers focus their cost reduction efforts on these low cost components although the potential savings, when compared to what could be achieved in other components such as magnetic steel and copper windings, are relatively negligible.
Some of the issues to consider are:
On time delivery
- It would be a shame not to be able to ship a $50,000 transformer because you are missing a $200 bushing.
Rush deliveries
- Anyone can make a mistake or receive a rush order. These are the times when your supplier should shine.
Possible defects
- Your supplier should only deliver bushings that are useable and look like they are useable.
- Some defects are not readily identifiable. If you are lucky, you will find these types of defects during your final electrical testing. If you are not lucky then you will find them when the transformer fails in the field.
Familiarity with your requirements and buying pattern
- Even if you design and specify the bushing configuration, there are times when things such as creep distance, strike distance termination type, and gasket surfaces, are overlooked. It is good to know that your supplier can recognize potential problems and suggest corrections before problem occur.
Procuring transformer bushings from off-shore suppliers will have its own issues.
Let’s face it, off-shore supplies usually represent only one thing and that is labour cost. Yes, chances are that locally manufactured components will cost more than those acquired off shore but one must also consider "value”. Just as you can take a bus or a plane to LA, one costing much less than the other, your choice will be based on how much "value” you place on your time. You must consider the ultimate "value” you will receive from your off-shore source.
One must ask:
- What am I really saving?
- How many parts do I have to purchase at a time?
- How much will it cost to ship my orders to my plant?
- How much inventory will I have to maintain?
- How fast can I get rush orders and how much will they cost?
- How do I know that my regular shipments will be of the same quality as the samples I approved?
- How do I detect potential quality problems?
- What are the consequences of quality problems?
One must consider the "total value" to be received from off-shore transactions and, more importantly, must develop contingency plans to avoid drastic consequences.
Bushings are relatively low cost items but play a critical role in the operation of the transformer. Since price is only one component of value, it is worth while to make sure you are receiving true "value" instead of just the lowest price.
