Frequency convertor

The probability of finding a new nonlinear crystal with such specific optical characteristics within a reasonable period of time depends on several factors. The first factor is the rate at which the relevant optical properties can be measured with sufficient accuracy to decide if the crystal is likely to be better than the ones already in hand. Second, there must be a reasonably high probability that the set of materials chosen for characterization contains crystals with the desired characteristics. Finally, assuming that crystals with the desired properties are only sparsely distributed among the set, tiie rate at which the crystals can be synthesized or otherwise obtained in characterizable form must be high, so that a large population of crystals can be scrutinized. The object of this paper is to review the strategy we have developed to optimize these factors in our search for improved ICF frequency convertors. 

It is important to note that, with the exception of the extraordinarily large aperture size requirement, the criteria for a fusion laser frequency convertor are generally applicable to any high power laser. Moreover, many of the ideas presented here are applicable, mutatis mutandis, to the search for NLO crystals for any specific application, for example, diode laser doubling. 

In the following, a fully pneumatically operated control and monitoring unit as a safety device is described for a Group I pressurized enclosure, e.g. for a frequency convertor. 

Pressurization opens the way to a large-scale integration of components such as transformers, circuit breakers and contactors as well as frequency convertors into a single enclosure, thus replacing the multiple-housing switchboards in... 

Figure 6.20 Pressurized frequency convertor during assembly at the manufacturer s site.

Figure 6.30 Natural gas compressor at Groningen gas field/The Netherlands. Motor - Pressurized non-salient pole (synchronous) motor, frequency convertor fed. Type of protection EEx pe [ib] NO T3 Rated power 23 000 kW at 5400 min-1 Speed range 600... 6300 min-1 Voltage up to 2 x 3600 V Current up to 2 x 2030 A ...

Figure 6.94 Longitudinal section drawing of a flameproof cage induction motor with integrated frequency convertor, stator housing water cooled.

Figure 6.95 Flameproof cage induction motor, with integrated piggyback frequency convertor.

Frequency convertors for motor drives with variable speed have shown reliability and cost reduction for some time. An example for application in coal mines is shown in Fig. 6.104. A frequency convertor with impressed current in the DC link is installed in two separated flameproof enclosures ... 

Figure 6.104 (a) Frequency convertor for coal mines (total view). The e -terminal compartment at the right side is used for both incoming and outgoing lines. 

Rated voltage 1000 V Max. motor rated power 511 kW Cooling water cooled Dimensions Height x width x depth 1000 x 2860 x 800 mm3 Added volume of flameproof compartments 1.5 m3 Weight (total) 3700 kg Type of protection EEx de I. (b) Frequency convertor according to Fig. 6.104(a), doors of flameproof compartments opened. 

Rotating electrical machines shall be tested at standstill and running with 0.9X 1.0X their rated speed. The rotor causes a certain turbulence of the test gas, resulting mainly in a considerably increased dp/dt value [2] and enhanced peak pressure. Cage induction motors may be fed from outside with an adjustable voltage and frequency via a frequency convertor, motors with sliprings or commutators need an auxiliary drive, e.g. a small cage induction motor powered by said frequency convertor. 

Frequency convertors - in the low voltage range - are designed according to flameproof enclosure - d - (Fig. 6.104) or to pressurization - p (Fig. 6.20), combined with e -terminal compartments for the most part. 

Similar considerations can be made for semiconductors in rectifiers and frequency convertors. The maximum load integral for semiconductors in power equipment can be assumed with values starting from 103A2s up to (and exceeding) 107A2s. 

These considerations can be summarized as a protective device for power cables in coal mines, low voltage switchgear, rectifiers and frequency convertors shall respond within one millisecond. To respond means to detect faults and subsequent fault current cut-off with isolation of network areas to be protected. The maximum load integral shall be limited to 103A2s (as an order of magnitude). 

---