Impulse levels

The impulse level in column 4 of Table 11.6 has been so chosen that the machine winding will have a sufficiently high level of insulation to fit into the system of insulation coordination, as discussed in Section 17.11 and Table 11.6. 

Table 13.2 Standard insulation (impulse) Levels for Series 1 range I voltage systems (1 kV < l/, < 245 kV)...

Switchgear and controlgear assemblies 13/345 Table 13.3 Standard insulation (impulse) levels for range II voltage systems (V , > 245 kV)... 

Note For proper protection, the impulse level of all protected equipment must be greater than the front of wave protective level by a margin of 25% or greater. 

Notes The impulse level values are read by a High Speed Graphic Recorder LP—50. Linear slow values are read by VM—14B. Differences commonly used between impulse level and first level are 3.5-4.5dB. 

Table 5.8 shows a summary of the results of the sound of explosions measured at the mock storage shed. Data is shown at the impulse level, and data from the fast level is usually 3.5-5.5dB lower than the impulse level data. Impulse levels were used for the dB values. The frequencies used for a linear response were l-90Hz for the special linear characteristic and 10-20Hz for the special flat characteristic. In many cases the explosive sound was measured over 100Hz to include the main components. One must pay close attention to methodology when comparing and analyzing measured values of sounds. 

The ventilation direction is highest at 10 m according to the noise and sonic pressure level, and lowest in the direction of the door where there is a the double wall. At 10m from the storage shed, the A characteristic impulse level is llOdB, and the Flat impulse level is not over 120dB. At 30m, the A characteristic impulse level is lOOdB, and the Flat impulse level is not over HOdB. 

Digital micropropulsion, consisting of an array of single-shot thrusters, has also been developed to provide short impulses for attitude control of miniature spacecraft. The approach consists of enclosing an explosive or propellant between a resistive heater and a burst diaphragm that leads to a nozzle etched in silicon. Impulse levels of 10 N/s for nun -scale thrusters have been demonstrated, with an 7sp of 11 s [9]. There is potential for finer impulse levels and better fuel utilization as the combustion process is mastered. 

The basic impulse level rating for a transformer winding identifies the transient overvoltage withstand capabihty of its insulation. 

A short-term voltage limitation is specified in lEC 62067 Annex G (informative) as impulse levels [13]. Considering short-term voltage limitation, the following phenomena are studied ... 

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