Electric shock test

The purpose of this test is to check for proper insulation of all the insulated live parts and components and to ensure protection of a human body against electrical shocks while the eqtiipment is energized and is in operation. The test detects weak insulation, if any, and this must be rectified before putting the equipment into service. 

An additional benefit of intrinsically safe systems is the reduction of electrical shock hazards. It is cautioned, however, that intrinsically safe systems are not necessarily tested specifically for personnel shock hazards. 

Other additional studies or pertinent information which lend support to this MRL Rats exposed to 1,000 ppm trichloroethylene for 3 days showed disturbed sleep cycles (Arito et al. 1993). Rats exposed to 250 ppm for less than 8 hours showed decreased electric shock avoidance and frequency of Skinner box lever press (Kishi et al. 1991). Humans exposed to 27 ppm trichloroethylene for up to 4 hours noted drowsiness, and headache was reported at 81 ppm (Nomiyama and Nomiyama 1977). Humans exposed for 8 hours to 110 ppm showed decreased performance on perception, memory, reaction time, and manual dexterity tests (Salvini et al. 1971). 

In the maximal electric shock (MES) test a supramaximal stimulus is applied bilaterally through corneal or auricular electrodes to induce tonic hind limb extension in rats or... 

The tests generally involve some form of maze but the simplest is the passive avoidance test. In this the animal learns that in a certain environment it will be punished with an electric shock for some particular action, like stepping onto a special part of the floor of the test chamber. The test of memory is how long the rat avoids (remains passive to) making the movement that will initiate the shock. Of course, drugs that reduce the animal s anxiety also modify the response. Using a maze in its simplest T shape, the animal is placed at the base of the vertical arm and a food reward at the end of one of the horizontal arms. Clearly the animal has to learn which arm contains the reward. Memory is assessed by the time taken for a food-deprived animal to reach the reward and the number of false arm entries. This simple system can be made more complex by introducing many more arms and branches but the principle is the same. 

An example for stimulus generalization are responses of rats to stress-inducing odors. Laboratoiy rats of the Wistar strain respond to predator odors, specifically mercapto compounds in fox droppings, with stress reactions, for example avoidance behavior such as freezing and increased plasma corticosterone concentrations (Vemet-Mauiy et ah, 1984). The rats were trained to avoid water scented with a mercapto odorant that contained both a keto- and a sulfhydryl group (4-mercapto-4-methyl-2-pentanone). As the animals licked a waterspout, a mild electric shock was applied to their tongue. When different compounds were tested thereafter, the rats avoided compounds with similar... 

Another behavioral approach used to assess aspects of anxiety in animals relies on conflict paradigms in combination with punishment, mostly induced by electric foot shock. Due to ethical and also ethological considerations, paradigms based on electric shock are less often used than tests for unconditioned anxiety. However, it has been hypothesized that behavioral expressions displayed in tests for unconditioned and conditioned anxiety may reflect profoundly different aspects of anxiety (File 1995 Griebel 1996 Millan and Brocco 2003). Thus, shock paradigms are quite frequently included in behav-... 

Passive avoidance. This test involves the use of a shuttle box, in which animals can move between a light side and a dark side. After an acclimatization period, in which the animal can move freely between the two sides, it receives a mild electric shock while in the dark (preferred) side. During subsequent trials, the time spent in the safe side is recorded. 

In lower mammals, scopolamine reduces the excitability of the motor areas as tested by electric shocks, and the reflex excitability in the frog is not increased as by atropine. Scopolamine appears to be excreted or destroyed in the tissues much more rapidly than atropine, for its effects last a shorter time. 

Arylgermatranes were more active than hetaryl derivatives in memory improvement tests (Table 11). Phenylgermatrane, p-tolylgermatrane, p-fluorophenylethynylgermatrane, benzylgermatrane and o- and p-bromobenzylgermatranes completely prevented animals from retrogradal amnesia caused by electric shock. 

At the present time we use a battery of three learning and memory tests. These are (1) Unlearned behavior is measured by activity (2) Ability for new learning is determined by comparing experimental and control animals on their time to learn to respond to a signal and retreat to a safe area thereby avoiding an electric shock and (3) Memory (or old learning) is measured by ability to press four levers in a given sequence for a receipt of a food reward. 

But the worm research did have some interesting spin-offs. Mice that were fed the brains and livers of other mice subjected to stress — researchers had rolled them around in glass jars — learned to associate a light stimulus with electric shock faster than other test animals. It seems that stress hormones transferred by diet enhanced learning. 

In the UK, the electricity supply is connected to earth. It is this system that enables earth faults on electrical equipment to be detected and the electrical supply to be cut off automatically. This automatic cut-off is performed by fuses or automatic circuit breakers if a fault occurs the fuse will blow and break the circuit. Although they do not eliminate the risk of electric shock, danger may be reduced by the use of a residual current device (RCD) designed to operate rapidly at small leakage currents. RCDs should only be considered as providing a second line of defence. It is essential to regularly operate the test trip button to maintain their effectiveness. 

Reinforced insulation. A single insulation system that provides a degree of protection against electrical shock equivalent to double insulation. It may comprise several layers to meet thickness and/or test requirements. 

Abnormal operation and fault conditions. Tests to limit risk of fire and electric shock from the equipment. Various abnormal operation and fault conditions are applied, such as electrical shorts/opens, component failures, mechanical faults, blocked vents, and overloads. The equipment s temperatures and electrical outputs are monitored during these tests. The product... 

---