Interstitial nephritis phenacetin abuse ยาแก้ปวด Stone.Patho มักเป็น อันเล็ก โตช้า low grade รูปร่าง อีกแบบ โตเร็ว aggressive ถ้า infiltrative เห็นเป็นแค่ หนาๆ thickening and induration of the ureteric or renal pelvic wall mildly enhancing bean-type renal mass involving the collecting system extending into the renal pelvis of left kidney (arrows).Other alternative is to work with the manufacturer to provide this information from the testing or design parameter such as of steel used on transformer, core design, etc. to determine the magnetizing current and other core parameters. If a fine accuracy is required for special applications, the transformer may be modeled using computer program such as PSPICE, EMTP, etc. Were: K= 12 for sizes above 3MVA selft cooling rating or K=8 for 5 Ipu=5.t^-0.6 – 1.8. There are two approach commonly used in the industry to draw the protective device selectivity coordination curve passing between the equipment damage curve and the Inrush criteria describe as follow:Īt 0.1 second for example the Inrush current will be Kx FLC of the power transformer Some of them those who reported not difficulties with Inrush current used relatively long time (1/3 to ½ sec.) or decrease sensitivity, or both. Inrush current had been identified to be the root cause of false tripping in 75% of survey response performed in various companies by IEEE.
CYME TCC FULL
Values of inrush current had been register during energization of the unit varying between 8 to 30 time the full load current with duration from 10 cycles in small units to 1 min in large transformers. The Inrush current in power transformers occurs when the polarity and magnitude of the residual flux do not agree with the polarity and magnitude of the instantaneous value of steady-state flux in the transformer core. As the losses damp the circuit, the saturation becomes less and L increases." RE: Transformer Inrush Current stevenal (Electrical) 7 Sep 01 18:32 During the first few cycles, the saturation is high hence, L is low. The time constant of the circuit (L/R) is not a constant because L is variable because of the transformer saturation. "The inrush current decays rapidly for the first few cycles, and then very slowly, sometimes taking 4 or 5 seconds to subside, where the resistance is low.
CYME TCC PLUS
Power transformers are operated normally near the knee of the saturation curve, so the additional flux requirement of zero-voltage-wave energization plus any residual flux will definitely saturate the iron and increase the magnetizing current components." If there is a residual flux left in the bank from the previous energization, it may either add or subtract from the total flux, thereby increasing or decreasing the inrush current. At this time, the current and flux should be a maximum in the highly inductive circuit, and a half wave of voltage requires a flux change of twice the maximum flux. "The maximum inrush current occurs if the transformer is energized when the voltage wave is near zero. A good explanation is given in the old Westinghouse Applied Protective Relaying book: Nbucska - transformers do have an inrush current.
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