Frame size

Frame size Shaft height for (Figure 1.17) motors (mm) Frame size Shaft height for (Figure L 7) motors (mm)... 

For a lower range of motors, say up to a frame size of 355, the silicon steel normally used for stator and rotor core laminations is universally 0.5-0.65 mm thick and possesses a high content of silicon for achieving better electromagnetic properties. The average content of silicon in such sheets is of the order of 1.3-0.8% and a core loss of roughly 2.3-3.6 W/kg, determined al a flux density of I W[ym and a frequency of 50 Hz. For medium-sized motors, in frames 400-710, silicon steel with a still better content of silicon, of the order of 1.3-1.8% having lower losses of the order of 2.3-1.8 W/kg is prefeired, with a thickness of lamination of 0.5-0.35 mm. 

For yet larger motors of frame sizes 710 and above, core losses play a more significant role, and require very effective cooling to dissipate the heat generated. Cooling of larger machines, complicated as it is in view of their size and bulk, necessitating core losses to be restricted as low as possible. 

A subsequent study of construction features of motors for Zone 2 locations, resulted in the development of nonsparking, type n motors. The basic design consideration for such motors is similar to that of type e motors but now there is no restriction in the limiting temperature, by 10°C, as in type e motors. Frame sizes for these motors are generally the same as for general-purpose motors. Thus they tend to be smaller and less expensive than type e motors for the same output. 

Frame size Poles Load distance 1 (mm) Maximum allowable load ... 

A crude method can be to set up two lamps at both ends of the stator housing after removing the end shields. This can be done in smaller motors, say, up to 355 frame sizes. 

Moment of inertia or stored energy constant, applicable to motors of frame sizes above 315 10% of the guaranteed value... 

In such cases it may ollen be possible to meet the requirement by selecting a higher frame size of MCB or MCCB, which inay possess a higher rupturing capacity also. If not, and to save on cost, one may provide HRC fuses for back-up protection. 

Table 17.1 Typical ratios of copper to insulation the turns per coil in smaller frame sizes...

Frame size Ratio oj copper Tarns pel coil Tarn insuhttion (Table 1.2) to insalalion to collage... 

Note For oui discussion, (he frame size 400 alone is more critical. Frame sizes, 500 and 630 are only indicative to illustrate the comparison. 

Energy Evaluation Chart NEMA Frame Size Motors, Induction... 

Select the frame size (hub diameter, d ) using Figure 6-9. At the inlet volume value, a 44 frame is selected with a maximum speed of 3,150 rpm. This frame has a 44-inch hub diameter... 

CliL Lk the hub-to-tip ratio, dh/d,. If greater than. 67, continue. If not, eo back 10 Step 2 and try another frame size. 

Gas turbine frame sizes are limited, and custom sizing is not done as it is with steam turbines therefore, the increment matching can only be done with a helper turbine. There is some benefit besides the power matching when used with a single-shaft turbine. The steam turbine can be used as the starter. For two-shaft turbines, a dedicated starter is needed on the gasifier turbine compressor package. 

Select the compressor frame from Table 12-9B for a typical example, not attempting to promote any particular manufacturer (each manufacturer has its own tables). Based on the inlet volume and the required discharge pressure, select frame size. 

Based on an inlet volume of 4,600 icfm and knowing the required discharge pressure is 225 psia, select a 29M frame size from Table 12-9B. 

For operation greater than 5,500 ft altitude, refer to factor for frame size and price. 

B. Frame size. (Usually applicable only when ordering replacement motors or for special applications. Size usually must be at least as large as manufacturer s standard for motor size and speed.)... 

NOTE Beginning in 1954, NEMA Standard frame size will be one number smaller for motor of 1-3 hp than previously, due to improvements in insulation requiring less space for wiring. It, therefore, will be advisable in ordering replacements in this range to state whether or not driven equipment was sized to take the former standard frame for this horsepower. 

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