1.1 Characteristics of motor


1.1.1 Starting characteristics
The instant load of motor at start-up is not so big since SELFJECTOR is driven by means of centrifugal friction clutch. Namely, at first the motor attains rated speed, and as the bowl is accelerated, torque of the friction clutch increases and soon the bowl attains the rated speed.
Therefore, it is necessary to use a motor designed to withstand start-up overload for several minutes.

Overload
Time
25%
30
50%
15
75%
5
100%
1


1.1.2 Characteristic curve at start-up

The characteristic curve at start-up may differ somewhat according to the type of machine and conditions of the friction clutch. The curve shown in Fig. 4.1 is one example for reference to select the motor.



NOTE

- ) Generally the value of electric current attains a peak prior to completion of start-up, but for some machines this is not clear.
- ) The value of electric current differs according to the feed rate.
- ) On sludge discharge, at time of feeding of sealing water and replacement water, the value of electric current shows an increase. It takes about one minute until the value of electric current returns to original value after discharge.


1.1.3 Output and revolution speed

In case the revolution speed of SELFJECTOR is lowered, its capacity is reduced and when it excessively rises, i t s safety decreases in terms of strength and vibration, etc., so the revolution speed shall conform to Table below.



Model
Rated output KW
Number of poles
Synchronous speed (rpm)
50 Hz
60Hz
SJ 20 T, P, EH
5.5
4
1500
1800
SJ 25 T, P, EH
7.5
4
1500
1800
SJ 30 T, P, EH
11
4
1500
1800
SJ 40 T, P, EH
15
4
1500
1800
SJ 60 T, P, EH
18.5
4
1500
1800
Characteristic curve at start-up

1.1.4 Others

Our standard motor is of Class B insulation and continuous rating. The ambient temperature should be below 5 0 degree Celsius an d even if supply voltage varies within 10% of rated voltage, the motor shall have no difficulty in practical use.



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