High voltage generators are being subject to higher voltage rating and are being designed to operate in harsh conditions. Stator windings are the main component of generators in which Electrical, magnetical and thermal stresses remain major failures for insulation degradation accelerated aging. A large number of generators failed due to stator winding problems, mainly insulation deterioration. ...

Design of Converter transformer insulation is a major challenge. The insulation of these transformers is stressed by both AC and DC voltages. Particle contamination is one of the major problems in insulation structures, as they generate partial discharges leading it to major failure of insulation. Similarly corona discharges occur in transformer insulation. This partial discharge due to particl...

High voltage generators are being subject to higher voltage rating and are being designed to operate in harsh conditions. Stator windings are the main component of generators in which Electrical, magnetically and thermal stresses remain major failures for insulation degradation accelerated aging. A large number of generators failed due to stator winding problems, mainly insulation deterioration...

Previously we have shown in dogs that tibial bone marrow and s.c. tissue temperatures are lower than rectal temperature during the plateau phase of whole body hyperthermia with the use of a radiant heating device. In an attempt to increase thermal dose to these sites during whole body hyperthermia, we applied insulation to an extremity prior to the plateau phase of heating. We found that extrem...

In modern traction propulsion applications, voltage source inverter (VSI) fed traction motors today operate very close to borderline conditions. With new emerging semiconductor technologies, higher inverter switching frequencies will be possible and high inverter dv/dt-rates appear, resulting in transient overvoltages at the machine which increase the stress on the insulation system and lead to...

The classic approach for determining insulating resistance by using commercial testers is not reliable for testing different types of insulation, especially for cables with one conductor and nanoelectronic oxide-based devices (nanotransistors). In this paper an alternative low-voltage method for measuring insulation resistance based on strongly increased current sensitivity is proposed. The pro...

In this contribution will be presented results from investigations on partial discharges (PD) in insulation systems, resembling the stator insulation in high voltage rotating machines. A model, simulating a stator winding in a slot, has been developed, consisting of simple rotating machine insulation test bars with epoxylmica insulation, mounted between steel sheets forming a slot, in order to ...

The main insulation system in high-voltage direct current (HVDC) transformer consists of oil-paper insulation. The formation of space charge in insulation paper is crucial for the dielectric strength. Unfortunately, space charge behavior changes because of the corrosive sulfur substance in oil. This paper presents the space charge behavior in insulation paper induced by copper sulfide generated...

Original scientific paper In electrical power system, variety of solid, liquid and gaseous materials are used for insulation target to protect the incipient failure inside the high voltage power transformers. The insulation is practically ended when the insulation system has become fragile enough to flourish cracks under the electrical and mechanical stresses to which it is subjected. The elect...

The development of obesity may be aggravated if obesity itself insulates against heat loss and thus diminishes the amount of food burnt for body temperature control. This would be particularly important under normal laboratory conditions where mice experience a chronic cold stress (at ≈20°C). We used Scholander plots (energy expenditure plotted against ambient temperature) to examine the insula...