A Power Transformer Monitor (PTM) is a specialized electrical utility device equipped with sensors that collect, process, and measure information relative to the current flowing through a distribution or power transformer. The process is known as condition monitoring of transformers and reports to a control system such as SCADA/MDM where an analytic platform can display interpretable transformer data.

 

What is the Origin of Transformer Monitoring?

The art of transformer monitoring dates to the early 1900s where techniques to measure oil temperature and simulated winding hotspot temperature were developed. These devices were primarily used to activate cooling fans to raise the power handling capacity of transformers and to start pumps, when needed, to circulate the insulating fluid to assist cooling the windings, core, and structural components. Many people in the industry still refer to devices that monitor power transformers a Transformer Temperature Monitor or Electronic Temperature Monitor or ETM.

What does a Transformer Temperature Monitor Do?

Transformer Monitors observe fluctuations in transformers and their electrical distribution system by assessing various parameters to predict and prevent the failure of a transformer.

How are Power Transformer Monitors Connected?

PTMs are usually connected to temperature sensors which are Resistor Temperature Devices (RTDs) for which there are thermometer wells installed in the tank. In the event that the transformer does not have a thermometer well, Advanced Power Technologies manufactures a convenient magnetic mount probe that is as intrinsically accurate as our thermometer and can be retrofitted onto any flat surface. In the event that winding temperature is needed, a split-core current transformer is supplied for continuously calculating the transformer’s winding hottest spot temperature. Multiple types of sensors can be connected to the PTM to monitor tap position of the OLTC, Bushing C1 capacitance just to name a few of the monitored parameters.

 

Transformer Failure: The Importance of Transformer Monitoring

Moving forward to today, more is known about the reasons why transformers fail. If the transformer’s insulation system is severely degraded, a through fault may cause the windings to move closer together and may cause a flash-over that may lead to a catastrophic failure of the transformer.

In addition, there is one necessary component, the transformer’s bushings that should its capacitor fail will lead to an equally catastrophic failure shown above.

Other components that may lead to the transformer failure is its On Load Tap Changer (OLTC or LTC) used in roughly 50% of all power transformers. In addition, the correct operation of the cooling system is paramount. Losing any of the fans or pumps will severely degrade the designed cooling capacity of the cooling system.

 

Why do Transformers Fail? What causes a Power Transformer Failure?

Transformer failures can occur due to various causes.

• Dielectric Breakdown
• Winding distortion caused by short circuit withstand
• Excessive winding and core hot spot
• Electrical disturbances such as a through fault
• Deterioration of insulation’s dielectric integrity
• Lightning
• Overload
• Inadequate Maintenance such as loose connections, insulating fluid leaks, cooling system failure
• Failure of accessories such as OLTCs
• Bushings

What happens when a Transformer Fails? Aftermath of a Transformer Failure

Transformer failures could cause power outages, personal and environmental hazards and expensive rerouting or purchase of power from other suppliers.

Transformer Monitoring Solutions – Transformer Temperature Monitor

Transformer monitoring solutions are required to analyze temperatures of the insulating fluid, in the main tank and OLTC tank. Also bushings need to be monitored on-line to avoid costly and catastrophic failures. Finally, transformer monitoring strategies are required to ensure the cooling system is in tip top shape and moist air is not allowed ingress into the transformer’s tank. At Advanced Power Technologies, we are constantly thinking about and developing technologies for effective and cost efficient Transformer Monitoring solutions and it is why Advanced Power Technologies should be your subject matter experts and trusted partner for all your Transformer Monitoring needs.

 

 

Expertise in Transformer Monitoring

Our philosophy and approach to transformer monitoring is: Information alone is not what your Company pays for, actionable information is. It is just data and who has the man power to sift through reams of data?

Our goal is to produce Expert Transformer Monitoring Systems that automatically analyze the data for key problem indicators of your Transformer’s health that allow our devices to reliably declare an exception and alert you at the earliest time.  Our Systems can definitively declare that there are the necessary key indicators to indicate a potential failure of the cooling system, serious problems within your OLTC that is indicative of an impending failure, and in the case of GIC predict when the transformer should have its loading reduced or taken out of service to protect it from failure by simply measuring the level of GIC and the harmonics that are on specific phases of the LV or HV side of the transformer.

We examine each issue individually and develop technical solutions that provide the highest quality and actionable information and in some cases take remedial action to give our customers the proper amount of time to take an outage and repair the issue before it is too late leading to unplanned outages and increased costs in material and your resources to resolve the issue. This is also known as Online Condition Monitoring.