Even though transformers are well-protected against malfunctions, they can still occur and create significant problems. Learn more about transformer protection systems by reading on. In every distribution system, transformers are a necessary instrument for manipulating voltage. Transformers are the most costly part of the distribution system, in addition to being one of the most important parts. Because of this, replacement and repair are extremely expensive tasks that must be completed promptly. Before we discuss transformer protection, let's examine some common transformer failures. They are primarily separated into two categories: internal and exterior defects. A sophisticated transformer safety relay system quickly resolves an external problem to prevent any threat to it. Sensors and measuring systems are mostly the source of internal defects. Luckily, wet transformers are covered in oil, and transformers are encased in static devices. These safety precautions usually reduce the number of errors even the best-laid plans can go wrong.
What Is Transformer Protection?
The phrase "transformer protection" can refer to a
wide range of protective upgrades and modifications that can be made to a
transformer. With differing levels of sensitivity, these devices detect
internal transformer problems that seriously
harm the device. Some can also offer
backup protection in the event of a breakdown. Current, voltage, frequency, oil
pressure, and temperature are just a few of the variables that these systems
are able to detect.
Why Is Transformer Protection Important?
There are other factors to take into account, but we've
previously discussed some of the financial rewards you can have for alerting
your personnel to transformer problems. For example, because downtime is also a
costly prospect, a fault might have a greater impact on your bottom line than
replacement prices. Protection is a crucial component used to minimize
disconnecting time and lower the risk of catastrophic failure. The longer you
keep a transformer operating under less-than-ideal circumstances, the more
likely you are to shorten its lifespan.
Transformer Protection Types and Methods
Together, these transformer protection types provide
extensive fault isolation and detection capabilities:
- Over-heating
protection
- Over-current
protection
- Differential
Protection of Transformer
- Earth
Fault Protection (Restricted)
- Buchholz
(Gas Detection) Relay
- Over-fluxing
protection
The whole protection system is divided into: 1)Electrical Protection and
2)Mechanical Protection.
Transformer Electrical Protection
Over Current/Earth Fault Protection:
You will need overcurrent protection in the event of phase
or ground faults. Under safe circumstances, electricity only powers the
transformer and flows without producing any extra heat. Transformers may
overload or short circuit when this flow is higher than usual. Fusible
connections, fuses, and circuit breakers are the most straightforward ways to
provide overcurrent safety. Each of these physical components has the ability
to restrict or even stop an electrical current's flow. Fortunately,
transformers are enclosed in static devices, and wet transformers are drenched
in oil. Typically, these safety measures make faults quite limited. However,
even the best-laid-out plans can go awry, which is why it’s crucial to employ
means of transformer protection. Read on to discover the common types of
transformer protection systems.
Overcurrent Protection
When phase or ground faults arise, you’re going to want
overcurrent protection. In safe conditions, electricity flows without
generating any excess heat and simply provides power to the transformer. When
this flow exceeds the normal amount, transformers can overload or short
circuit. The simplest means of providing overcurrent protection is with fusible
links, fuses, and circuit breakers. All these pieces of hardware can limit or
even disable the flow of an electrical current. Keep in mind that this hardware
will not correct the overcurrent problem. Instead, they will stop the flow of
electricity by tripping circuit breakers and blowing the fusible links. For
small transformers with ratings under 10 MVA, HRC fuses are utilized. In the
absence of differential protection, overcurrent relays serve as the main line
of defense. Overcurrent protection is utilized as a backup measure if
differential protection is employed.
Overheating Protection
Under Impedance/Distance Relay Protection:
For transformers connected to networks, OC protection is not
appropriate for backup protection. When the maximum and minimum short circuit
fault MVAs differ significantly, relay protection is necessary under impedance
or distance.
Differential Current Protection:
The phase currents on both sides of the transformer that has to be protected are compared by the differential protection relay. The relay sends out an operational signal if the phase current differential in one of the phases is greater than the value of the function's instantaneous protection stage or stabilized operation characteristic.
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| Application of Differential Protection Source: electengmaterials.com |
Over-Fluxing Protection:
Over-fluxing is an example of raising the magnetic flux
density to an extreme point, just like overcurrent is an example of exceeding
the typical electrical current to a transformer. Overheating and subsequent
internal problems, which can be extremely expensive to fix, can result from
this increase. Overcurrent protection and over-fluxing protection function
similarly. The circuit breaker will be instructed to trip by the system when
the flux density ratio rises to a hazardous level. By doing this, you can stop
further harm to your transformer and shut it off.
Transformer Mechanical Protection
Oil Temperature Trip Relay:
When an internal defect occurs, such as insulation failure
in one winding phase and shorting or the creation of a small hotspot, this
relay detects the temperature of the oil and transfers the generated
temperature to the oil, heating it. This oil temperature relay activates when
the oil temperature rises above a predetermined point.
Buchholz Gas Detection Relay:
A Buchholz relay is a specialized mechanism designed to safeguard your transformer against minor or serious malfunctions. Your transformer will have oil in the Buchholz relay when it is functioning properly. In the event of an internal malfunction, gas bubbles created in the transformer tank will instead fill the Buchholz relay. The Buchholz relay's alarm element is activated by the accumulation of these gas bubbles.
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| Buchholz Relay Source: circuitdigest.com |
The
Buchholz relay will secondary activate a trip element if the issue is not
resolved in a timely manner. This happens when significant defects cause rapid
oil loss. In a nutshell, a Buchholz gas-detection relay allows you to try to
solve an issue and then acts as a backup if you are unable to.
Conclusion
Make sure your facility has all the protective systems it needs now that you are aware of these typical transformer protection system kinds. An ounce of prevention is worth a pound of cure, as the adage goes. Remember that being proactive can ultimately save you a significant amount of money.
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