CEC provide a range of services for oil filtration and the testing of oil and insulation used in electrical power transformers. As part of our High Voltage Maintenance, our expert staff have a detailed knowledge of transformer diagnostics and can provide detailed current and historical reports to assist in the maintenance of transformers. We also offer oil filtration services. We facilitate the collection, transportation and processing of used non-PCB and PCB-contaminated naphthenic-based transformer oil from power utilities, electrical maintenance companies, used oil collectors and other sources. CEC also provide instruction around the collection of samples using approved sample containers to send the samples to our testing facilities.

CEC’s minespec Transformer Oil Filtration unit and 4WD service truck travel the East Coast of Australia servicing councils, mines & industrial clients. CEC are experts in HV installation and maintenance, and onsite Transformer Oil Filtration forms part of CEC’s overall HV maintenance.

Onsite Transformer Oil Filtration restores the oil to its new state. The filtration process removes acidity, sludge and soluble oil decay products from the transformer windings and cooling system.

The filtration process lowers operating temperatures of the transformer, which helps prevent recontamination. The desired outcome of onsite Transformer Oil Filtration is to maintain the insulating properties of the Transformer Oil. This can be achieved with the optimum seven year cycle. This will allow the integrity of the transformer oil to remain intact and prevent costs by not only increasing the life of the transformer, but also reducing the probability of an unplanned outage. 

To handle electrical stresses, transformer oils are required to have better dielectric strength. Lower residual water, gas and contamination content must be maintained to reduce the speed of oil ageing. All of these operations are performed using CEC’s onsite transformer oil filtration unit.

Power transformer oil filtration, dehydrating and degassing can be performed individually or simultaneously based on the various conditions of the mineral oil and customer requirements.

  • Dissolved gas analysis
  • Moisture content
  • Dielectric breakdown
  • Dielectric dissipation factor (DDF) and D.C. resistivity
  • Acidity (neutralisation value)
  • Furans
  • Interfacial tension (IFT)
  • Antioxidant (DBPC, DBDS, etc.) / passivator (Irgamet39, BTA, etc.) concentration
  • Degree of polymerisation of paper (DPv)
  • PCB contamination (solids, liquids, surfaces)
  • Particle count and profile
  • Viscosity
  • Density
  • Flash / pour point


At CEC, our main concerns are safety and quality assurance. This is why the most important part of the construction of a HV installation is to test the system in order to ensure it is fit for purpose and use. As part of our High Voltage Maintenance, we implement rigorous quality assurance processes of functional and relay protection testing, in order to test:

  • System design
  • Equipment specification
  • Installation and wiring
  • Setting calculations
  • Device programming
  • IEC61850 testing

CEC’s protection relay testing specialist will provide the client with a report that fully documents the curve of the relay, and the points on the curve that were tested. This is an important aspect, because it allows a relay to be trended over a period of time.

Beyond Earth Leakage and Overcurrent, the Differential Relay Report shows the curve and the points where the relay was tested to trip, and where it was tested to correctly not trip.


With the increasing dependency of back up systems on battery strings, and the escalating cost of replacing batteries, instrumentation and software systems that can measure, trend and manage the life-cycle of cells is a cost effective option.

As part of its High Voltage Maintenance, CEC can test a battery bank at constant current, constant power, or using a user-defined load profile. CEC can also test battery chargers and other electrical equipment that require resistive load testing.

CEC can:

• Test batteries “in service”

• Unit adjusts to include load currents in the test parameters

• User adjustable alarm and shutdown points to avoid excessive discharge

•Provide digital report with graph on how battery performed, this allows trending.

Full Load Battery Testing.  CEC Callaghan Electrical Contractors perform full load battery testing. This test is often performed online so there is no disturbance to operation. The batteries are tested with a full load applied and the results are graphed and reported.

It is important to implement a Battery Testing regime to test protection batteries, because in the event of a major fault – current spikes and voltage drops, which means the control circuit doesn’t have the required voltage to operate the shunt trip – and if the battery back-up fails the fault will not be cleared.

Routine Battery Load Testing will detect any issues with battery during normal operation so any issues can be resolved before a major fault happens.

There are three main reasons to test battery systems:

-To insure the supported equipment is adequately backed-up

-To prevent unexpected failures by tracking the battery’s health

-To forewarn death

There are three basic questions that battery users ask:

-What is the capacity and the condition of the battery now?

-When will it need to be replaced?

-What can be done to improve / not reduce its life?

Batteries are complex chemical mechanisms. They have numerous components from grids,active material, posts, jar and cover, etc. – any of which can fail.


As part of its High Voltage Maintenance, CEC offers an exhaustive transformer maintenance and testing program. We understand the need for intelligent preventative maintenance and rapid response repair. Our transformer maintenance services include:

  • Repairs (leaking radiators)
  • Upgrades (LTC and voltage regulator relays)
  • Electrical testing
  • Oil testing and analysis
  • Emergencies, 24 hour support
  • Assembly and set-up
  • Commissioning service
  • Radio testing
  • Replacement parts sales
  • Nameplate Data
  • Power Meggering
  • Auxiliary Components and Wire Checks
  • Lightning Arrestors
  • Hand Meggering
  • Temperature Devices
  • CT Tests
  • Winding Temperature and Thermal Image
  • Bushing Power Factoring
  • Remote Temperature Indication
  • Transformer Power Factoring
  • Auxiliary Power
  • Voltage Ratio
  • Automatic Transfer Switch
  • Polarity
  • Cooling System
  • Transformer-Turns Ratio
  • Bushing Potential Device
  • Tap Changers
  • Auxiliary-Equipment Protection and Alarms
  • Short-Circuit Impedance
  • Overall Loading
  • Zero Sequence
  • Trip Checks
  • Winding Resistance

Switchyard Maintenance

Switchyard maintenance is an integral part of high voltage electrical systems management. Incorrect maintenance systems can result in power failure and massive disruption to your business. As part of its High Voltage Maintenance, CEC provides a holistic suite of supply, project management, construction, testing and commissioning services for switchyards.

High Voltage Maintenance & Circuit Breaker Maintenance

Circuit breakers are used in almost all electrical systems and are integral in protecting them from damaging over currents and short circuits. As part of its High Voltage Maintenance, CEC are experts in the operation of all circuit breakers, including;

  • Repairs & maintenance of all types of low voltage & high voltage circuit breakers.
  • Power factor correction unit maintenance & repair
  • C/Ts & V/Ts maintenance & repairs
  • ABS maintenance & repairs
  • Medium voltage air magnetic (MVACB)
  • Medium voltage vacuum (MVVCB)

Earth Mat Testing

Our High Voltage experts are fully qualified to conduct earth mat testing for large earth systems. Comprehensive testing and records are vital to ensure earthing meets design criteria, and we can also schedule and implement periodical preventative maintenance to ensure corrosion or changes in the soil’s resistivity do not have an adverse affect on the earthing system.