2 Calculation of the loading diagram and choosing the motor capacity by its heating

2.1 Initial data

2.1.1 Oblique lift, which was overviewed in the Chapter 1, is taken as working mechanism for which loading diagram of electric drive is calculated and previously choosing by the capacity motor is checked by the heating conditions.

2.1.2 Lift works in intermittent duty.

2.1.3 Cycle of motor work includes next operations (Fig.2.1)

а) load of the cart during time t₀₁ (табл. 2.1);

b) rheostatic start, fatigue movement and electric plugging till the full stop during lifting the cart with nominal load (time t_n1, t_y1, t_Т1 in the Fig. 2.1);

c) unloading of the cart during time t₀₂ (Table. 2.1);

d) the same as in b), but during lowering of empty cart (time t_n2, t_y2, t_Т2 in the Fig. 2.1);

2.1.4 During loading and unloading periods the motor is switched-off and the cart is kept with the help of electromechanical breaker.

2.2 The task

2.2.1 To define the start time, the time of electric breaking and the time of steady movement during lifting of loaded cart and descending of empty cart and also cycle time and duration of motor switching-on.

Comment. The data about static moments and moments of inertia, reduced to the motor shaft, startup and breaking characteristics are taken from the Chapter 1, items 1.3.3, 1.3.5, Fig. 1.6 during calculation startup and breaking time oscillation phenomena of rope elasticity can be neglected, i.e. consider system at .

2.2.2 To construct simplified loading diagrams M = f(t) and velocity diagram V = f(t) of electric drive (Fig. 2.1), changing at the start and breaking time the actual exponential dependence of the moment and the velocity in function of time by segments of the straight line.

2.2.3 To determine the equivalent moment of the motor during working cycle from the loading diagrams and make an inference about possibility to use chosen in the Chapter 1 electric motor to work on obtained loading diagram.

Table 2.1 – Output data in variants.

Variant number	Lifting way L, m	Time, s
		Loading t01	Unloading t02
1	8	60	60
2	10	80	70
3	12	50	40
4	15	100	90
5	20	45	45
6	25	35	35
7	20	70	60
8	30	30	зо
9	6	40	20
10	40	260	180
11	10	30	30
12	5	20	20
13	20	100	100
14	25	120	60
15	30	180	45
16	35	100	100
17	5	15	15
18	6	40	30
19	50	200	100
20	48	170	110
21	46	120	120
22	45	200	150
23	9	90	90
24	40	80	80
25	20	95	95

Extension of the table 2.1.

Variant number	Lifting way L, м	Time, s
		Loading t01	Unloading t02
26	8	60	60
27	10	80	70
28	12	50	40
29	15	100	90
30	20	45	45
31	25	35	35
32	20	70	60
33	30	30	30
34	6	40	20
35	40	260	180
36	10	30	30
37	5	20	20
38	20	100	100
39	25	120	60
40	30	180	45
41	35	100	100
42	5	15	15
43	6	40	30
44	50	200	100
45	48	170	110
46	46	120	120
47	45	200	150
48	9	90	90
49	40	80	80
50	20	95	95