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Transformer Repair vs Buy New, Pros and Cons


Transformers  tend to be reliable pieces of electrical equipment and if not abused, last for 30,40, 50+ years depending on their application and operating environment.  Failure rates vary from <1% for Power Transformers to 1-2% for Distribution Transformers.  Notwithstanding, all transformers will eventually fail, there is no cure for old age.


The transformer owner may have some advance warning of the impending doom if there is regular monitoring of transformer condition with oil testing and regular maintenance.  Some transformer operators will systematically remove transformers from service in advance of a failure, and other will run the equipment to failure.  Despite the transformer owners' best intentions, often a transformer will fail as the results of an unpredictable event such as a lightning strike, voltage surge, failure of adjacent equipment or the "last straw" of a life well lived.


Factors Affecting the Repair vs the Buy New Options

Size and Age

It is typically not practical to rewind transformers that are smaller than 1500kVA.  It will be cheaper and faster to look for a used replacement or a new replacement transformer.


Transformers older than 50 years tend to be poor candidates for extensive repair since the loss characteristics core laminations are much pooer than more modern transformers and the total economic evaluation points to new replacement unless there are extenuating circumstance such as fast turn around time or the need to exactly match the original tank/bushing configuration.


Turn Around Time

Depending on the failure damage, the usual cycle time for a rewind is less than buying a new transformer because of the Repair Facilities ability to focus on the project dependent of course on Factory loading.



Again, depending on the failure damage, repair can be an economical choice.  Even the worst case scenario of a three-phase complete re-wind, the core, tank and accessories will be reused resulting in a significant price advantage over buying new.


3L2R Inc. Capabilities

3L2R Inc. has a 40 Ton crane capacity with 36 ft. to the hook which enables the handling of transformers up to - 25 MVA at a voltage rating of 120 kV.  Our winding machines have the capacity of making larger windings than the crane size/headroom limiting capability.

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EATON breakers are globally certified including IEC, CCC, UL® and CSA® standards. 

3L2R in house support and stock enables you to order readily available product for on-time delivery requirements. 

Thermal-magnetic units are available with adjustable magnetic and thermal settings options.  Frame sizes from 15A to 125A, 15A to 225A, 45A to 600A , 300A to 800A, 320A to 1200A and 700A to 2500A.  Interrupting ratings go from 14KA (at 600V) right up to 100KA with the current limiter option on some breakers, models are FDB, FD, HFD, KD, HKD, KDC, JD, HJD, JDC, LD, HLD, and LDB for the popular ones. 

Many of these breakers come with a host of accessories like auxiliary contacts and switches, alarm switches, shunt trips and under voltage releases along with certain termination packages, interlocks and more!  

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Electrical switchgear regulates, protects, and isolates a power system with a variety of controls housed in a metal enclosure. It’s a vital system in industries that experience electrical faults or those that need to regularly de-energize equipment for maintenance, such as industrial environments and electrical utilities.


Switchgear contains fuses, switches, and other power conductors. However, circuit breakers are the most common component found in switchgear. During an electrical fault, a circuit breaker will sense the anomaly and interrupt the power flow, effectively limiting damage to the system.


Because it’s designed to control the flow of power, switchgear plays a role in enhancing a facility’s energy efficiency and safety.


There are different types of switchgear, most applications require either low voltage switchgear or medium voltage switchgear.

Low voltage switchgear is used across multiple industries such as healthcare, industrial buildings, and water/wastewater to regulate systems up to 1 kilovolt. Depending on your facility’s specifications, you can incorporate different product features, including:



Front access

Space-saving design


Indoor and outdoor systems up to 75 kilovolts use medium voltage switchgear. Since applications and budgets vary, medium voltage equipment comes in three insulating technology options:


Gas-insulated switchgear

Air-insulated switchgear

Shielded solid switchgear


Insulators protect the components within the switchgear and often provide a cooling function.


There are differences between switchgear and switchboards although many use the terms interchangeably.  Not only does switchgear protect and control the power supply, but it also can disconnect from a power supply during a fault. On the other hand, switchboards are only used to transmit power to other sources, most often in commercial settings.  Switchgear and switchboards are also designed to handle different voltage capacities. High voltage switchgear can accommodate up to 350 kilovolts, whereas switchboards are rarely designed to handle more than 600 volts.

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Inside of every motor control center is a collection of MCC buckets, otherwise known as wrappers.


These are the modular, partially-enclosed components of the motor control center and contain a collection of motor starters, relays, variable frequency drives or soft starters and other components that control motor-based equipment.


The large number of low-voltage MCC circuits results in significantly more human interaction time with low-voltage MCC equipment than with medium-voltage MCCs and switchgear simply due to the volume of these circuits in the market place.  Proactive maintenance indicators based on load characteristics, motor start characteristics and thermal measurements are something to monitor for a reliable MCC system. Factors like time synchronization, Ethernet-based protocols, sequence of events records, monitoring and alarming for protection functions, and other standard features in protective relays. 


The reliability, functionality, programmability, flexibility, and intelligence of an older smart MCC protection, metering, and control IEDs are something to keep an eye on and parts for these are hard to come by.  

Here at 3L2R we stock Allen Bradley 2100 series, Eaton / Westinghouse Freedom 2100 series, Square-D Model 3, 4, 5 and 6 and other vintage models.

We can professionally remanufacture these buckets or simply provide a good refurbished fully tested unit.

Whether you need just a fusible or a breaker type unit for isolation or programable starter, call us today to see how we can help.

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Auto Transformer vs Isolation Transformer


What is auto type transformer? Auto transformers have one voltage winding, shared by both sides.  The term "auto" refers to a single coil acting alone, not to any kind of automatic mechanism.  You tap the winding along its length to provide some of the primary voltage across its second load.  You should use auto transformers in applications where you need to step up or step down on three-phase line voltages.


Advantages of an auto transformer:

  • Cheap and more efficient
  • Less leakage inductance between primary and secondary, thus less losses
  • Simple construction to the OEM
  • Smaller footprint for same VA rating


The primary purpose of an auto transformer is to regulate the voltage of transmission lines and can be used to transform voltages.  With only one winding, an auto transformer adjusts the voltage automatically according to load.  These transformers call for AC currents to operate correctly and will not function on direct current.


Application for auto transformers can include:

  • Used as a starter to give up to 50 to 60% of full voltage to the starter of a squirrel cage induction motor during starting up
  • Used to give a small boost to a distribution cable, to correct the voltage drop 
  • Used as a voltage regulator
  • Used in power transmission and distribution systems, audio system and railways simply to act as a voltage changer


Now what is an isolation transformer?  This is a true transformer in a sense it does transformer the voltage between windings, it is an electrical transformer with a primary and secondary coil winding.  These windings are separated by insulation which limits the risk of electrocution when the active parts and earth are touched simultaneously.  They deliver a better power quality, safer, fewer surges pass through them and are typically not as noisy as other transformer types.


Advantages of an isolation Transformer:

  • Better power quality
  • Noise reduction
  • Reduces surges
  • Safety


The primary purpose of an isolation transformer is to isolate circuits.  These transformers are designed and manufactured with attention to capacitive coupling between the two windings.  Capacitance between primary and secondary windings would also couple alternating current (AC) current from the primary to the secondary.


Applications for isolation transformers can include:

  • For preventing data corruption and failure in computers using hard disc
  • The protection of telecommunication and data communication equipment
  • For the patient's safety while using machines like ECG, EEG or EMG pacemakers or any electrosurgical aid 
  • Clear recording in audio and video recording equipment
  • For error free data in process control instruments 
  • The elimination of earthing problem in electrical installations
  • The protection of CNC/PLC equipment from surges/spikes
  • Reduction of electrical noise or harmonics in the system for a specific design or level


Contact 3L2R Inc. today for an evaluation of your specific transformer needs, whether it is an isolation transformer vs and auto transformer


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The Current

Monthly newsletter - March 2021 Edition


Regardless of the measuring device you are using, calibration is crucial for ensuring specific and accurate measurements.

Calibration defines the quality of your measurements used by particular devices because over time results can change slightly as the devices age or are affected by a variety of environmental factors.  In order to uphold a high level of confidence, you need to have an ongoing process of regular maintenance and calibration for your equipment and devices.  Otherwise, you risk slight (or eventually significant) fluctuations in the accuracy of the measurements being collected, which can have extensive practical implications that you want to actively avoid.

Many people do a field comparison check of two meters, and call them "calibrated"  if they give the same reading.  This is not calibration, it is simply a field check.  It can show you if there's a problem, but it can't show you which meter is right.  If both meters are out of calibration by the same amount and in the same direction, it won't show you anything.  Nor will it show you any trending - you won't know your instrument is headed for an "out of cal"  condition.

Calibration, in its purest sense, is the comparison of an instrument to a known standard.  Proper calibration involves use of a NIST-traceable standard - one that has paperwork showing it compares correctly to a chain of standards going back to a master standard maintained by the National Institute of Standards and Technology.

At 3L2R in Cambridge, Ontario we offer a comprehensive and fully certified calibration service program for electrical and mechanical equipment.  You can drop-off your company's measuring devices or we can arrange on-site services for stationary equipment.  For customers in need of scheduled calibration we offer pre-booking with reminders.  Call (519)629-0152 to book your next calibration service.

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Calibration Services & Repairs

Ask yourself these questions?  

1. Do you need to be compliant on a yearly basis for testing equipment?

2. Do you need your equipment to run at Optimum Efficiency?


If you have answered yes to any of these two questions, then we at 3L2R can assist you with ensuring your electrical and mechanical equipment is compliant and running at its optimum efficiency. 


3L2R offers Calibration Services & Repairs to ensure your electrical and mechancial equipment provides you with accurate results in accordance with its specifications.  Did you know that it is recommended that you have your electrical and mechanical equipment calibrated on a regular basis?


Contact us at 519-620-0152 to book your equipment in for calibration services.





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Mike Raposo
November 17, 2021
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