Transformer oil sampling methods:
1, sampling with a syringe:?
The sampling valve of the equipment should be equipped with a connector with a small mouth, in the small mouth on the hose. Before sampling should be excluded from the sampling line and the sampling valve in the air and "dead oil", while flushing the pipeline with the body of the equipment oil (less oil equipment may not carry out this step). The oil flow should be smooth when taking oil samples. When sampling with a syringe, it is best to connect a small metal three-way valve between the syringe and the hose. Sampling method with syringe schematic diagram, as shown in Figure 8-7, in Figure a, glass syringe 5, and take oil samples between the connector 1 first connected to a small three-way valve 2, and then the three-way valve is rotated to the position shown in Figure a, so that the dead oil through the three-way valve drain. Then turn the three-way valve to the position shown in Fig. b, so that a small amount of oil enters the glass syringe and flushes the connector 3, the straight-through valve 4, the hose as well as the syringe. Thereafter turn the three-way valve to the position shown in figure c to allow the oil and air in the glass syringe to be drained off, and the process of b and c above can be repeated 2-3 times. Turn the three-way valve to the position shown in Fig. d. The oil sample will automatically enter the syringe under the action of the hydrostatic head of the oil, and the core of the syringe should not be drawn at this time, so as to avoid sucking in air, as well as the emergence of a vacuum inside the glass syringe, which will degas the oil sample and affect the accuracy of the analysis. Oil samples taken to a sufficient number, you can close the three-way valve and through the valve, as shown in Figure e, and remove the glass syringe, that is, with a small rubber tip closed glass syringe, small rubber tip air should be exhausted as far as possible, the sampling process will end. The core of the glass syringe should be clean and dry to avoid jamming.
Sampling with a syringe schematic?
a) Flush the connecting tube; b) Wet and flush the syringe; c) Empty the syringe; d) Take the oil sample; e) Remove the syringe ?
1- oil sample taking connector; 2- three-way valve; 3- connector; 4- straight-through valve; 5- hose; 6- glass syringe; 7- transformer body ?
2. Sampling with a brown mill-necked bottle: ?
1), the sampling container to be used with a capacity of lkg has a frosted glass stopper brown glass bottle. Wash with gasoline, soap solution or trisodium phosphate, and then wash with water and distilled water, drying, so that the oil sample bottle clean and dry, the stopper will be tight. After sampling to be labeled.
2), before sampling should be clean and hairless silk or fine white cloth will be clean around the sampling port, with transformer oil will be rinsed three times the oil sample bottle.
3), the operation of the equipment should be sampled from the lower oil drain valve. ?
4), to determine the sampling site should follow two principles: First, the sample should be able to represent the overall, the second is to take samples from the oil quality may be the worst part. "On behalf of the overall" is to avoid taking the stagnation in a dead end, there is a suspicion of external contamination of the oil. "The worst part of the oil quality" means that when the sampling valve is more than one, so that the quality of the oil taken out of it may be the worst one. In general, if there is a pipeline between the sampling valve and the main body oil, the oil in the pipeline is considered to be the dead center oil. For transformers with sampling valves at the top, middle and bottom, the oil taken from the bottom sampling valve is considered to be the oil with the highest probability of deterioration.
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5), sampling should be done as soon as possible after the test. Oil dissolved gas analysis of oil samples, from sampling to test, the interval should not exceed 4 days; water content, gas content test oil samples should not exceed 7 days; breakdown voltage oil samples, in the dry winter and spring seasons, the interval should not be more than 3 days, in the hot and humid summer, the shorter the interval the better, as far as possible to avoid taking samples from the field and take them back to the laboratory to do the test.
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6), the oil drum and no oil release valve of the small transformer sampling. Sampling by the oil drum in the operation method is as follows: ?
①, before opening the lid, you need to use clean cotton gauze or fine cloth without lint to wipe the outside of the lid, and then use a clean sampling tube to take samples. If you use a pre-washed and dried glass tube for sampling, you should insert the tube into the oil and use your thumb to press the top of the tube, and then put the tube into the bottle, release the thumb, let the oil into the bottle, do not use your mouth to suck the oil into the tube. When raising the glass tube rotate it on one side and release the oil in the tube to wash the sampling tube. This is repeated twice, and then suck the oil sample.
②, the sample oil should be taken from the bottom of the most serious contamination, if necessary, can also be taken from the upper part of the sample (sampling should be rolled or shaken before the oil drum, so that the oil is mixed evenly).
3, in the whole batch of oil barrel sampling, sampling the number of barrels should be sufficient to represent the quality of the oil batch. Generally two samples can be taken for the test; a mixed sample, that is, taken from the bottom of a representative number of containers of oil samples, and mixed evenly; a single sample, that is, the sample taken from the bottom of a container. ?
7), for the high-voltage casing that needs to be sampled, the oil is taken from the sampling hole when the power is out for maintenance.