Transformer Protection & Transformer Protection Circuits(3)

 

Transformer Protection & Transformer Protection Circuits(3)

 

When a fault circumstance takes place, we have sparks between the windings or in among windings and the center. These small electric discharges in the windings will warmness the insulating oil, and the oil will ruin down. Consequently, it produces gases, the severity of the breakdown detects which glasses are created.

A massive electricity discharge can have a production of acetylene, and as you could recognize, acetylene takes a number of electricity to be produced. And you need to continually remember the fact that any kind of fault will produce gases; through reading the quantity of gasoline, we can locate the severity of the fault.

How does Buchholz (Gas Detection) Relay work?

As you can see from the photograph, we've two floats: an upper waft and a decreased flow, also. We've got a baffle plate that is pushing down the decrease glide.

When a large electric fault occurs, it produces lots of fuel than the gas flows through the pipe, which shifts the baffle plate and that forces the lower floated down, now we have a combination, the upper flow is up, and the decreased flow is down, and the baffle plate has tilted. This aggregate shows that a massive fault has come about. Which shuts down the transformer and additionally generates an alarm. The photo beneath shows precisely that,!!

But this isn't the best state of affairs in which this relay can be useful, imagine a scenario wherein the transformer there's a minor arcking that is taking place, these arks are generating a small amount of gas, this gas produces a pressure in the relay and the higher drift gets down displacing the oil inside it, now the relay generates an alarm in this situation, the higher drift is down, the lower go with the flow is unchanged, and the baffle plate is unchanged if this configuration is detected, we may be certain that we have got a sluggish accumulation of gasoline. The picture under shows precisely that,

Now we know we have a fault, and we will bleed out a number of the gasoline the usage of the valve above the relay and examine the gasoline to discover the exact reason for this fuel build-up.

This relay also can hit upon situations wherein the insulating oil level falls due to leaks inside the transformer chassis; in that condition, the upper float drops, the lower waft drops, and the baffle plate stays inside the same function. In this circumstance, we get a specific alarm. The image below suggests the work.

Over-fluxing Protection

A transformer is designed to function at a hard and fast-flux level exceed that flux degree, and the center gets saturated; the saturation of the middle reasons heating within the center that quickly follows through the other elements of the transformer that leads to overheating of additives, as a consequence over flux safety will become essential, as it protects the transformer core. Over-flux situations can arise because of overvoltage or a reduction in machine frequency.

To defend the transformer from over-fluxing, the over-fluxing relay is used. The over-fluxing relay measures the ratio of Voltage / Frequency to calculate the flux density in the middle. A fast increase inside the voltage because of transients inside the electricity machine can motive over fluxing. However, transients die down fast; consequently, the instant tripping of the transformer is unwanted.

The flux density is at once proportional to the ratio of voltage to frequency(V/f), and the tool must stumble on the ratio if the fee of this ratio becomes greater than unity, that is done by a microcontroller-based totally relay which measures the voltage and the frequency in actual-time, then it calculates the rate and compares it with the pre-calculated values. The relay is programmed for an inverse particular minimal time (IDMT characteristics). But the putting can be achieved manually if that may be a requirement. In this way, the reason may be served without compromising the over-flux protections. Now, we see how crucial it's far to prevent the tripping of the transformer from over-fluxing.

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