Pre-terminated cables such as transformer leads in padmount substations should be tested as per this SWP. They are classed as minor radial cables and do not require a high voltage withstand test. Regarding the use of DC testing such as insulationresistance or leakage measurement during a high voltage DC withstand, there is a phenomenon called electro endosmosis (evident in older insulation rather than XLPE) that causes a lower IR reading (higher leakage current) when the positive terminal is connected to the grounded side of the insulation being tested.
Each memorised result is equipped with an eventual sub result and parameters of the measurement (see table 4). Each function has an identification number (1 t/m 3 see figure below). The user is able to identify the function where the sub result belongs to. The identification number is displayed for a while only, before the recalled results are displayed.
Displays a measured value during a test or the set value of the upper or lower resistance in any case other than a test in progress. For resis- tance measurements during the test, if the measurement range has been exceeded, the resistance value on the resistance meter blinks to notify the operator that the resistance is beyond the measurement range. However, the following indications apply when the tester has been switched to system mode by pressing the  VOLT (SYSTEM) key with the  LOCAL (SHIFT) key held down.
The insulationresistance needs to be checked prior to commissioning and again after any extended periods of storage or periods during which the equipment is not in operation. Before you begin measuring the insulationresistance, please read the manual of the insulationresistance meter you are going to use. Any cables of the main circuit, which are already connected should be disconnected from the terminals in order to carry out the insulation measurements.
A similar system can be installed in DC bus systems, e.g. a photovoltaic (PV) grid coupled system with DC bus and inverter with transformer (fig. 3). The transformer provides galvanic insulation from the distribution grid. This insulation transformer is mostly integrated in the inverter. In this case an insulation fault on the DC bus will not propagate to the AC distribution grid. By consequence the DC bus needs to be protected and this can be done with a RCD. Therefore the star point of the PV array needs to be earthed. A DC RCD can be installed and will detect any single insulation failure caused after the RCD. In this system a failure is only detected after the RCD and thus not in one side, e.g. the DC source or PV panel itself which is a serious disadvantage for PV applications. The RCD technology for DC systems is also quite complicated because a DC current measurement transformer has to be used. RCDs could be installed in multiple locations in the DC bus and they would be capable of locating faults but this features is not very useful for PV applications. An insulation failure caused by human contact will result in human electrocution due to the current flow and a first contact failure is therefore unsafe. A symmetric insulation fault is one with an identical insulation failure on the positive and negative voltage terminal. This kind of fault is not detected with an RCD because both currents are identical(+ and -).
The Cu wire together with its insulation ﬁrst underwent mechanical deformation during the squeezing stage and presented an indentation on the wire, but the insulation was not observed to be mechanically broken down or displaced from the Cu wire due to the limited electrode force (up to 6 N) and the good ductibility of the polyurethane coating. The insulation was heated afterwards by the upper electrode tip when the preheating current passing through. It was observed that the top layer of the insulation was melted in tens of milliseconds, while the bottom layer insulation remained unmelted (Fig. 4). The molten insulation rapidly shrank back due to the heat conduction along the wire. When the preheat time was extended up to 120 ms with a current of 200 A, the bottom layer insulation was also melted; the current was then conducted to the lower electrode and the welding stage was initiated. The heat required to melt the insulation depends on the melting temperature and the thickness of the insulation. So there exists a lowest required heat to melt both sides of the insulation. If the heat input was lower than the value, the welding stage would not initiate due to the impediment of the bottom layer insulation. However, excessive heat input is also not advisable. In this case, surface splash and carbon- ization of the insulation might be caused, which will contaminate the electrode tip and the base metal, thus,
The tests of long-term temperature resistance are based on reaction kinetics patterns. If one type of unimolecular reaction, pseudomolecular reaction resp., is the control reaction of temperature ageing in a certain interval, according to Arrheniov´s law or Büssing´s theorem there is a relation between the temperature and the concentration of materials entering the reaction in the course of time. However, more control reactions with different activation energies can proceed in a given temperature interval. They can have different temperature dependences of reactions speed. Such a case may occur when in the lower part of the time interval there is a dominant reaction with lower temperature dependence and in the upper part there is a reaction with higher temperature dependence of speed. The above described effect will manifest itself in dependence of time logarithm on reciprocal value of absolute temperature, by deflection from assumed linear dependence.
Abstract: A manufacture’s own criteria have to be fulfilled in addition to requirements specified by customers and applicable standards. Manufacturers test thousands of distribution as well as power transformer at worldwide location each week. In this paper , I wish to give an overview about different test conducted in distribution as well as power transformer of rating up to 11KVA TO 25 MVA .Equipment use in testing single phase dimmer stat, multimeter, digital voltmeter, digital insulationresistance, tong tester, MCB, fuse, banana connector, switches, testing wire connecting wire.Testing of any electrical equipment indicate the extent to which the equipment is able to comply with customer’s requirements .In this paper testing of distribution as well as power transformer considered.
The type of clothing worn by people directly affects the heat exchange between the human body and the environment. The heat transfer is both sensible (conduction, convection, and radiation) and latent (evaporation). The insulation provided by a clothing ensemble is dependent upon the designs and materials used in the component garments, the amount of body surface area covered by clothing, distribution of the fabric layers over the body, looseness or tightness of fit, and the increased surface area for heat loss. Insulation measurements made on fabrics alone do not take these factors into account. Measurements of the resistance to dry heat loss provided by clothing can be used to determine the thermal comfort or stress of people in cold to comfortable environments. However, the moisture permeability of clothing is more important in environmental conditions where heat balance can only be achieved by the evaporation of sweat.
When the peak loads are considered, it is observed that the average reduction in cooling load is obtained as 9.78 % in summer season and 9.26 % in winter when 150 mm thick insulation of EPS is replaced by 100 mm thickness of PUF. Although thickening of insulation produces effective savings on the annual energy consumption of the cold storage building, the insulation material cost also has to be considered. The reduction of cooling loads due to change in thickness of insulation for 100 mm, 125 mm, and 150 mm EPS and 100 mm PUF for the design days are given in the table below. Thus, from the simulation results it is clear that the amount of annual energy required for cooling can be reduced by Rs. 63875 per year due to replacement of EPS by PUF insulation. But additional cost of investment for PUF insulation can be recovered in 11.82 years.
A device for footw ear quality estim ation and physiologic sim ulation o f the hum an foot w as presented. The system calculates the therm al and evaporative resistance to estim ate the quality o f the footwear. T he m anikin can sim ulate therm al behaviors o f the foot and sw eating o f the foot. There are m any built-in functions for control o f the foot heating and sweating.
dynamic resistance is measured by dividing magnitude of actual tip voltage by the magnitude of current. This algorithm is based on the assumption that the resistance information is con- tained in each individual harmonics. This technique provides continuous measurements for the tip voltage and resistance, and is independent of the error caused by the change in area en- compassed by the wires attached to the electrodes. Moreover, the proposed method also have potential to identify expulsion of metal during the weld process. It is observed by Malhotra  that this method can only measures the slowing varying resistance component and is inca- pable of measuring 120 Hz sinusoidal resistance. This issue will be discussed in detail later in this thesis.
In conducting and semiconducting materials, changes in geometry, changes in length, width, and thickness of the material, due to mechanical stress causes a change in resistance of the material . Furthermore due to changes in interatomic spacing, as a result from mechanical strain, affect the bandgaps in the materials themselves  making it either easier or harder for electrons to be raised into the conduction band and therefore changing the resistivity of the material. These two effects can be used in order to make a sensor that can accurately sense what force is applied to it by measuring the change in resistance of the sensor.
The insulation is laid horizontally over the whole area of the floor. Insulation boards should be tightly butted, and cut to fit tightly at edges and around service penetrations. Care should be taken to prevent damage or dislodgement of insulation during floor laying. If the dpm is placed below the insulation, the joints between insulation boards should be taped to prevent wet screed from entering when being poured. If the slab/screed is power-floated, the exposed edges of perimeter insulation should be protected during power-floating, e.g. by boards, or the areas close to the edge of the floor should be hand trowelled.
(2) The thermal conductivities of the near-dried GFCs are in a range of 0.15 to 0.48 W/m·K when their demolded densities change from 720 to 1600 kg/m 3 (105°C oven-drying densities from 585 to 1370 kg/m 3 ) as the foam dosage decreases from 16% to 0. In this regard, GFC exhibits better thermal insulation property than normal PC foam concrete at the same density. (3) The GFCs derived from alkali activation of low-calcium fly ash possess excellent strength retention after high temperature treatment; the compressive strength increases by 100% after exposure at 800°C. However, slag substitution for fly ash causes a large strength loss after heating, which is attributed to the loss of structural integrity of the calcium-rich components of the binder gel.
A proper earth electrode resistance tester should be used to measure earth electrode resistance. An alternating current at 50 Hz of a steady value is passed between the earth electrode T and an auxiliary earth electrode T1 placed at a separation distance recommended by the manufacturer of the tester but in any case should not be less than 20 metres away. A second auxiliary earth electrode T2, which may be a metal spike driven into the ground, is then inserted half-way between T and T1, and the voltage drop between T and T2, divided by the current flowing between T and T1, gives a measured earth electrode resistance of earth electrode T.
The demand for thick wood-based board has increased since the Building Standard Law of Japan was revised and the Construction Material Recycling Act was enforced. Publishing the fire performance of thick wood-based boards would contribute to the development of fireproof, quasi-fireproof, or fire-preventive wooden construction materials. When evaluating the fire resistance test for walls or floors, the insulation criterion is an especially important factor.
Currently, in Japan, standards and guidelines such like CASBEE and “Explanation of the energy- saving standards for houses” are indicated the performance about inside insulation and outside insulation of exterior walls and floors. However, these discussions are not including the consideration about interior walls and ceiling, which also has a high heat capacity to affect the indoor thermal comfort and energy use. Meanwhile, heat loss through Heat Bridge is also a big issue of building thermal performance. In this section, thermal resistance and thermal transmittance are calculated following equation 1 and 2, and the results are showing in table 1. The total heat loss by thermal transmittance of the unit model is calculated according to equation 3 and the unit construction and volum, and the result is shown in figure 3.