100% duty cycle

The duty cycle is an essential temporal characteristic of mass spectrometers [1]. It is defined as the ratio of the time spent on the collection of ions for analysis to the operation time of the ion source within a complete scan. It is typically expressed as a percentage. This parameter 

The duty cycle of important mass spectrometers varies significantly. Under general working conditions, the duty cycle is 100% forMALDI-TOF-MS, 30% forQ-TOF-MS, 10% for IT-MS, -0.1% for S-MS and QMF, and -0.01% for FT-MS. 

Note It is not the duty cycle alone that reduces the transmission of oaTOF analyzers. In practice, the overall sensitivity of instruments is also influenced by ion losses during entrance into the orthogonal accelerator, divergence of ions prior to pulsing, eventual grids in the flight path, etc. 

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N = operation under rated conditions / = at rest and de-energized and 6, = temperature rise reached during one duty cycle ( -= 0)... 

For this duty cycle, the abbreviation is followed by the indication of the cyclic duration factor, the number of duty cycles per hour (c/h) and the factor of inertia (Ff). (See Section 3.4 for FI.) Thus, for a 40% CDF with 90 operating cycles per hour and factor of inertia of 2.5, the cycle will be represented by... 

This is a sequence of identical duly cycles, each consisting of a period of operation at constant load and a period of operation at no-load. The repeat load and no-load periods are just adequate to attain thermal equilibrium during one duly cycle. There is no rest and de-energizing period, (Figure 3.6). Unless otherwise specified, the duration of the duty cycle will be 10 minutes. 

N = operation under rated conditions V = operation on no-load and 0, = temperature rise attained during one duty cycle = corresponding to the no-load heating... 

For this duty cycle also, the abbreviation is followed by the indication of number of cycles per hour and the F . For example, for 300 c/h and FI 2.5... 

We have considered three different speeds (lower Ni to higher /V/ ,) for this duty cycle, having three CDF , for one cycle, each corresponding to a different speed. 

This is a type of duty in which load and speed both vary non-periodically, unlike the periodic duty cycles noted above. The motor now supplies variable load demands at varying speeds and varying overloads, but within the permissible temperature rise limits. It is a duty similar to duty cycle axcept that sometimes the overloads may exceed the full load but are within the thermal withstand limit of the motor (Figure 3.9) ... 

The nearest standard rating to this is 7.5 kW, and a motor of this rating will suit the duty cycle. To ensure that it can also meet the torque requirement of 10.5 kW, it should have a minimum pull-out torque of 10.5/7.5 or 140% with the slip at this point as low as possible so that when operating at 140%... 

Duty cycle and duty rating of resistance units 5/90... 

The resistance units, when used only for starting purpose, are in the circuit for only a short time and are thus short-time rated. However, when they are employed for speed control, braking or plugging operations, in addition to the starting duty, they may be rated for continuous duty. The resistance units are thus classified according to their duty demand, i.e. number of operations per hour (c/h). See Chapter 3 on the duty cycle. 

V and/of the fixed a.c. input supply or 4 and (phasor control) in the machine s parameters and use these to perform a required duty cycle with very precise speed control. 

This output coixesponds to a continuous duty of drive. It must be suitably corrected for the duty cycle the motor has to perform (see equation (3,11)), i.e. 

Correct this output also depending upon the duty cycle as noted in equation (3.12), i.e. 

Duty types. S, S, and. S5 as discussed in Chapter 3 are normally applicable to crane and hoist motors. For duty types S4 and 5. the duty cycle per unit time is greater than S, . The most important factor is the number of switching operations per hour. A temperature rise in the motor occurs during acceleration, braking and reversing. 

Loads of welding sets, which have intermittent duty cycles, are mostly single phase, cause low p.f. and stress the generator windings intermittently. Unbalanced loads, such as single phase loads, distributed unevenly cause current unbalance and low p.f. 

Such types of loads may require special design of capacitor elements and their dielectric impregnation, cooling arrangement, size of shell or surface treatment. For all these applications therefore it is important to know the actual operating conditions, behaviour and characteristic of the load and its duty cycle before selecting the capacitors. 

Duty cycles Continuous duty (CMR) (S ) Periodic duties Factor of inertia (FI) Pleating and cooling characteristic curves Drawing the thermal curves Rating of short motors Equivalent output of short time duties Shock loading and use of a flywheel... 

Bury (1974 1975 1978 1999) introduces the concept of duty cycles to static design in a different approach. The duty cycle or mission length of a design is equivalent to the number of load applications, however, it is only the maximum value which is of design significance. If the load, L, is a random variable then so is its maximum value, L, and the PDFs of each are related. It can be shown that the CDF, F L), of the maximum among independent observations on L is ... 

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