Voltage frequency converter

A piston driven stretching device has been developed by Koch et al. Stretching occurred in a fraction of a second. The sample can be heated by a stream of hot air. For stretching velocities up to 0.75 mm s , a stretching device has been developed by Holland Moritz and Stach which can also be used for real time fourier transformed infrared (FTIR) experiments. Both the force and elongation are transferred to a PDF 11/24 computer by a CAMAC based voltage/frequency converter (Fig. 31). 

Table 1. Ingedrive MV100 medium voltage frequency converter technical features...

Voltage-frequency converter Fast response Continuous output Moderate precision Telemetry... 

The maximum count rate stated for an FC is actually a limitation imposed by the counting electronics of the SIMS instrument. In short, this is a function of the maximum input voltage of the voltage/frequency converter divided by the charge of an electron (1.602 x 10 C) times the value of the resistor placed across the input and output thermals of the impedance amplifier. Assuming for the sake of argument, values of 10 V and 10 M 2 are applied, which results in an upper count rate of 6 x 10 cps. 

As with FCs, the current recorded by the respective EM must first be converted to a voltage. This is carried out using a high impedance amplifier. This voltage is then passed onto a voltage/frequency converter to allow the signal to be relayed in units of cps. Once the noise associated with these types of detectors is removed (see Section 4.2.3.3.2.1), EMs are easily capable of recording individual ion counts per... 

Voltage source inverter (VSl) using IGBTs 6/125 Current source inverter (CSl) 6/126 Cyclo converters (frequency converters) 6/127 The regenerative schemes 6/127... 

Variable AC voltage and frequency converter (IGBT or thyristor)... 

For controlled-potential coulometry the voltage drop over a standard resistor is measured as a function of time by means of a voltage-to-frequency converter the output signal consists of a time-variant and integrally increasing number of counts (e.g., 10 counts mV-1), which by means of an operational amplifier-capacitor yields the current-time curve and integral158. 

There is a shortest reasonable exposure time that is related to the frequency of the heartbeat quartz and the adjustment of the voltage-to-frequency converters. Below the reasonable exposure interval quantization errors become a problem and the measured value will be chosen from a small number of possible steps. 

Voltage-to-frequencv-converters (V/F). The applied input voltage is converted into an oscillation with a frequency proportional to the input voltage. The resulting frequency is measured within fixed time intervals. 

With a frequency converter, stator voltage and frequency of the asynchronous motor can be varied infinitely. This transforms a standard motor into a variable speed drive system. An asynchronous motor equipped with a rotor position sensor, magnetization calculation, and the impression of the corresponding stator currents (vector regulation) has the properties of a servo drive. 

Voltage peaks also arise from the semiconductors switching in the inverter stressing the insulation of connected motors. For this reason, motors intended for inverter operation are better insulated. Sometimes - depending on the length of the motor cable - output filters are provided between the frequency converter and the motor to protect the latter. Such measures should be undertaken when standard motors used initially at constant speed on the mains are retrofitted with an inverter for variable drive. 

Whereas further effects are determined by the frequency converter, this effect is determined by the asymmetry of the motor itself. The voltage levels arising here typically range below 500 mVpeak which, under normal conditions, does not cause trouble. These bearing voltages cannot be entirely eliminated, but can be reduced by precise adjustment of the air gap. One... 

Circular currents cannot be influenced by grounding measures. The size of the current depends on the size of the windings and the steepness of voltage slope in pulsed motor voltage. Thus, circular currents can be reduced by a filter between the frequency converter and the motor. This effect has practical significance for frame sizes above 280. 

The frequency converter s voltage wave form can be changed to a degree at the frequency converter. Using an output filter also alters voltage wave form. These filters were mainly developed to minimize high-frequency common-mode interference voltage, but they reduce circular currents as well. 

It is possible to equip large extruders with fully variable drives. In this case, speed variability is often not the main intention, but rather the fact that the existing supply network does not permit a fixed-speed motor to be started, because other users on the same network would be starved by the drop in voltage. In such cases, a frequency converter offers the advantage that much less current is required for start-up. Starting currents can of course also be reduced by a starting transformer or a softstarter. 

A frequency converter can also be used as a starting aid and also does not have to be configured for full power. However, since it often cannot be operated at motor voltage, both an inverter-transformer for voltage reduction in front of the frequency converter, as well as a motor transformer for voltage increase after the frequency converter have to be used. All three components are bridged after starting, to run at full power. 

Thus the Josephson junction can be an excellent DC voltage-to-microwave-frequency converter the factor ine/h is approximately equal to 3 x 1014Hz. 

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