ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 21 
curves, Fig. 10, indicate the different thicknesses of 
miecanite tubes and oil cloth required for different working 
pressures. 
8000 Wee 
al 
_ 
8 X gehe— 
= 
o (02 4 V6 
LEMCKNEES LV LIVE ‘ 
Fig. 10.—AVERAGE THICKNESSES OF SLOT INSULATION 
FOR DIFFERENT VOLTAGES. 
In laying out the curves of Fig. 10, the bending and pressing 
of the material inside the slot is allowed for and they 
give full safety against a testing pressure double that of 
the normal.. 
43. Other Materials.—Oil cloth, specially prepared for alter- 
nating current work, is a most suitable material for 
medium pressure, and it may be used together with press- 
TABLE 5.—-SAFE THICKNESSES OF PRESS-BOARD 
FOR DIFFERENT PRESSURES. 
Thickness in Pressure in Thickness in Pressure in 
Inches. Volts. luches. ‘Uils. 
01 igs .06 2,858 
02 400 07 8,650 
03 900 .O8 4,500 
04 1.500 09 5,500 
<06 2,100 .10 6,500 
board, or for high tension work with micanite. Press- 
board has very good mechanical qualities; it can be bent 
over curves of the smallest radius and its insulating quality 
against puncture is a good one, see Table 5. Fibre is a 
