IEC TS 62332-1:2011 pdf – Electrical insulation systems(EIS)- Thermal evaluation of combined liquid and solid components – Part 1: General requirements.
4.2.6 Safety system
A pressure relief valve shall be installed on each cell to prevent the internal cell pressure to raise above equipment capability.
NOTE For low thickness walls (e.g.l.2 mm). valves controlling a pressure 0* 35 kPa woId be suttvaent and for higher wall thicknesses teg. 8 mm) valves controlling a pressure 0* 85 kPa could be u,tab*e In any case the prelsur. Should be calculated.
An over-temperature protection device shall be provided, responding to the temperature sensors in both the liquid and the test object in each cell. The sensors for the over- temperature protection shall be independent of the sensors for temperature control.
4.3 MonitorIng and data collectIon
The output of all temperature sensing devices shall be monitored. Any deviations from the set-point range f or more than 1 h shall be recorded hourly until corrected,
5 Construction of the test object
5.1 General
The test object is designed to model the EIS portion of the electrotechnical products under
evaluation and usually consists of
• a current-carrying conductor,
• a conductor insulation,
• insulation spacers/barriers,
• a liquid.
Other components may be used as appropriate.
52 Determination of component volumes
it is important that the ratios of volumes of components used to construct the test object shall be representative of the electrotechnical product being modelled. Therefore the total volume of the individual components in the products shall be evaluated. Determine the percentage of each Individual component as a part of the total volume. The percentages shall be used to determine the volume of those individual components to be used in the construction of the test obtect. in a family of products with the same specific EIS, the ratio of volume of the individual components to the total volume should be similar.
NOTE I The liquid volume Is determined at 20 C.
An example Is included In Annex A for calculating the volumes and dimensions of the components.
NOTE 2 Add.1.onal components may be macned into the ageimig cell in order to achieve the best balance between temperature and volume requirements.
5.3 Test object
5.3.1 General
The following test obiect represents a llquid•immersed coil, which includes the liquid and solid components of the EIS.
The conductor terminals, which pass through the end-plate, shall be brazed to the conductor and fixed In the end-plate.
The conductor shall be insulated as required by the volume ratios determined from 5.2. As an example experience has shown that using pre-cut tensile strips of the width of the bare conductor is the best way to evaluate conductor insulation. The bare conductor should be wrapped with conductor insulation, tensile strips added and then the whole assembly be again wrapped with conductor insulation to keep the test strips as close to the conductor loop as possible.
A suitable device shall be used for temperature measurement and control. The location on the conductor loop where the tensile strips are located should be as close to the thermocouple which is monitoring/controlling the conductor temperature as possible. In this way these test strips are at the correct temperature for the thermal evaluation method.
NOTE 1 Two type K (chroniel-alumel) therriiocoupi.s or a resistance temperature detector (RTO could be Installed securely on the surface 04 the conckacior for temperature measurement and control. Additional thermocouples may be included.
NOTE 2 Thermocouples containing iron present a potential Oudation probtem.
The conductor assembly shall have a thermal barrier to establish a temperature gradient between the conductor and the liquid. The material for the thermal barrier shall be one of the ElM used in the test object. Pressboards are usually employed as mechanical electrical support for conductors in the electrotechnical product being simulated. Thermal barriers shall be secured to the conductor assembly by means of an Inert tie.
5.3.3 Liquid component
The cell shall be tilled with the liquid component used in the electrotechnical product being evaluated. The volume of the liquid shall be determined from requirements In 5.2 based on volume and temperature calculations.