Specifications

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Drive motor: The most popular type of motor used in a washing machine is a single phase, 230
V, 50 Hz, capacitor start and run squirrel cage induction motor. These motor may range from 1/
3 to 1/2 hp rating. These motors are normally protected from overload and overheating conditions
by means of a bimetallic overload relay or a thermal switch. The motor is located in such way
that water leakages do not fall on to these motors.
Working of semi-automatic washing machine: The semi-automatic type washing machines
are relatively simple in operation and construction. It consists of two separate tubs names as
wash tub and spin tub as shown in Fig.12.8. The washing cycle in such a type of machine would
consist of the user filling the wash tub with water upto the required water level. The water level
can be set, according to quantity of cloths, using water level selector. Soap and bleach are to be
added. Depending upon the types of the clothes to be washed, the ‘ON’ time or wash time of the
machine is to set and the machine is switched ‘ON’. Most machines have the agitator directly
driven with out any intermediate gears as shown in Fig. 12.8.
Fig. 12.8 - Twin tubs of semi-automatic washing machine
After the washing is completed as per set time, the water from the wash tub should be
drained out. Fresh water is to be filled for rinsing purpose to remove detergent form fabric.
Required time is to be set manually. The clothes after being rinsed are placed in the spin tub and
it is rotated at high speed. Due to the centrifugal action, the water from the clothes is removed
fully till it is just damp dry. The time duration for spin operation is to be set manually with the help
of spin timer. After spin cycle is over, take the clothes out and dry them in suitable place.
Advantages:
1) It is applicable for low and medium budget people as the cost is less by 30% to 50%
when compared to fully automatic washing machine.
2) The wash time can be set manually hence electric energy can be saved.
3) It is also suitable in places having no water tank and pipe line.
Disadvantages:
1) As the name indicates, partial work has to be done manually like pouring water, changing
clothes from one tub to another and expelling of water.
2) Very few models have in-built heater facility.
3) Should be handled carefully or else it may lead to leakage of water.