Unique Facilities and Superior Experience

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Big enough to accommodate a mid-sized car or a 10 metre tall distribution pole, and powerful enough to flashover a 500 kV insulator, Kinectrics’ Environmental Testing Chamber is unique in the world.

Proven methodology

Two pre-set test methods are designed to establish the electrical insulator dimensions required for adequate winter performance. Kinectrics’ Cold-Fog Method has received international recognition as the correct test for setting winter leakage distance needs. The Contamination-Ice- Fog Melting Temperature Test (CIFT) is the most severe test of dry-arc distance. No EHV power system should be designed without this data if it is to be exposed to an urban, winter environment.

Customized profiles of icing and melting scenarios have also been designed and carried out to match clients’ observations, data needs, as well as test methods proposed by Kinectrics’ research collaborators. Standard mechanical test methods are also performed for items such as switches.

Inclement condition modeling

Typical storms associated with HV and EHV insulator flashovers are frequently characterized by:

• Initial air temperature below freezing, possibly as low as –10^oC
• Temperature rising through 0^oC over a period of several hours
• Light freezing rain or freezing drizzle, followed by light to heavy fog
• Relative humidity maintained near 100% for the entire period
• Moderate wind, in range of 10km/h (6mph)

Test parameters

These base conditions can be reproduced in Kinectrics’ environmental chamber day after day, at any time of the year. Additional details controlled during testing are:

• Rain rate, droplet size, pre-chilled water temperature and temperature-corrected electrical conductivity. Cold floor to simulate frozen ground.
• Fog particle size distribution, fog density and conductivity to match natural observations.
• Uniform temperature from top to bottom of the chamber.
• Uniform wind speed with low turbulence intensity.

Environmental Chamber Specifications

• Dedicated 370 kV rms AC, 60 Hz, 20 A from 350 kV, 1666 kVA outdoor transformer.
• Impulse and switching voltage surges from nearby 2000 kV, 100 kJ surge generator.
• 20,000 A for conductor de-icing studies and cable termination testing from a 200 MVA supply.
• Temperature is controlled from –10^o C to +40^oC within 0.2C^o. Near 0^oC, rates of change from 0.3 to 30 C^o/h are possible. Floor is cooled separately.
• Electric heaters and steam injection allow elevated temperature testing.
• Wind can be varied from 0 to 13 km/h using two banks of 16 fans, each with independent speed control. Fans provide stable airflow through the cooling towers (1m w. x 5m h. zone).
• Twenty-four fixed and 12 oscillating rain nozzles provide uniform coverage with water of controlled temperature and conductivity, for both vertical and horizontal orientations.
• Fixed rain nozzles use time cycling and interchangeable nozzles to establish droplet sizes and rain rate. The super cooling distance is a minimum of 2 m.
• Eight ultrasonic nozzles normally inject 5-10 μm fog particles of controlled conductivity. Fog density exceeding 0.3 g/m3 with 10-15 μm drop size can be set up and maintained for 24 hours.
• Steam can be produced and stored in an external 70-m³ reservoir. Steam can be introduced in a rapid and controlled fashion, with minimum stratification using a full-height diffuser.

Superior temperature control

Maintaining 94-100% relative humidity and dense fog in freezing temperatures puts unique demands on heat-exchanger design. Incorporating the following essential design features ensures uniform conditions and minimal condensation:

• Two-stage refrigeration system, using glycol for an intermediate coolant
• Heat exchanger surface area of over 400 m²
• Generous spacing of fins to accommodate frosting
• Air flow up to three times the chamber volume per minute through each heat exchanger column

Large area heat transfer surfaces and high airflow rates result in less than 0.01C^o temperature change each time the air passes through a cooling coil. Very little condensation occurs, even at 99% relative humidity. Cooling coil temperatures typically remain less than 1C^o below ambient, and are excellent indicators of the measured dew point. This Kinectrics’ icing chamber characteristic is unmatched in any other EHV facility.

Embedded "ice-rink" coils and an independent glycol loop in the chamber floor allow it to be cooled independently and maintained at, or below the chamber air temperature. Other auxiliary systems provide rapid venting to the outdoors and heat-tracing to prevent freezing of the rain system, remote-control video cameras, and high intensity lighting.

Insulator surface contamination is a dominant factor in cold-fog performance. Kinectrics offers a range of dry and wet pre-contamination methods to match any desired soluble/non-soluble pollution levels.

The Environmental Testing Chamber’s generous dimensions and large face area of the heat exchanger/wind columns allow testing of many different insulator configurations and large equipment units such as switch assemblies. Side-by-side comparison tests of vertical insulators can be readily accommodated.

For more information, contact

John Page, 416.207.6492, john.page@kinectrics.com

Related links:

High Voltage Testing Services