Page 195 - Industrial Power Engineering and Applications Handbook

Special-purpose motors 7/175
I Non-return valve p7
REhr Cable - llr

h-1 ,-Cable

Mining type
Bearing bush
Discharge casin, -cable box
Bearing sleeve
Pump bowl
'mpellerY
Casing wear ring
Bearing sleeve

Coupling
Suction strainer arrangement,
if provided
(details not shown)
Suction casing
Sand guard
Radial shaft seal
Cable
,- gland
Motor bearing
bush
Motor bearing
housing (upper)

Figure 7.8 Sectional arrangement of a submersible squirrel cage
motor of 860 kW, 30, 50 Hz, 3.3 kV, 1470 r.p.m. (Weir pumps)

Winding
I
11 Ill IBl Motor bearing bush
Thrust bearina Refineries
plat6 3 Chemical and process plant duties
Thrust bearing Thrust bearing ring
housin -
9
Breath( ir Water filling- 7.6 Motors for agricultural
diaphragm cum-drain plug application

In developing countries particularly, rural power
Figure 7.7 Nomenclature of a submersible pump set distribution networks normally suffer from wide voltage
according to IS 9283 fluctuations. This is generally because of LT loads which
cause a high voltage dip. Consequently, the motors are
designed for voltages as low as 415 V -20% to +5% and
Deep-sea mining for manganese nodules etc. (Figure generally 415 V-12 3 %, i.e. 360V. For such high voltage
7.9). Many riches lie on the seabed. To explore this fluctua-tions, the general practice is to select a motor
hidden wealth, submersible pumps have proved to be larger than normal. These motors may be designed for a
a boon. Figure 7.9 shows the arrangement of a general low starting torque, in view of their applications for pumps,
seabed exploration. Here three submersible pumps have winnowers, threshers etc., all requiring low starting
been used in series, encased in a shrouding to extract torques. The rotor can also be designed for a low starting
and lift manganese nodules from a depth of over current, and thus protect the network from a high starting
5000 m to the sea surface voltage dip.