1.2 The task
1.2.1 Define static stresses on the reel rim in all four lift modes, ignoring the weight of the rope.
1.2.2 Identify the moments on the reel shaft and static moments which are kept to a motor shaft for the four modes and powers on the motor shaft, assuming that the elevating speed and speed of descent of the loaded and empty cart is unchangeable and equal to nominal velocity. 1.2.3 Define reduced to the motor shaft moments of inertia of lift winch (consisting of the motor, brakes, reduction gear and reel), cart (with and without load) and counterweight for startup and braking. Find the total moment of inertia of entire electric drive system.
1.2.4 Define reduced to motor shaft cart rope branch rigidity to its lower position (Fig. 1.1a). Make a chart of calculation of mechanical elastic medium (Fig. 1.2), considering that reduction gear, motor, reel and short-branch counterbalance shafts rigidity equal to infinity with respect to the rigidity of cart rope long branch. To make a block diagram (Fig. 1.3) and transfer function for the control action for the mechanical elastic medium. Identify the rope data from the table 1.6.
Figure 1.2 – Scheme of mechanical elastic medium.
Figure 1.3 – Block diagram.
Table 1.6 – Initial data.
Variant number |
Rope |
|
Diameter, mm |
Summarized sectional area, mm2 |
|
1,2,4,7,8,12,17,18,19,20,24 |
17 |
108,3 |
3,5,6,9,10,11,21,22,23 |
20 |
151,3 |
13,14,15,16,25 |
22 |
175,5 |
1.2.5 For pre-selected motor of lift winch (Table 2.1 -1.5) it’s necessary to calculate and construct natural and artificial characteristics ω=f(M), and ω = f (I) in absolute and relative units (Fig. 1.4, 1.5). To build artificial characteristics of rheostat way of motor speed changing at given conditions: at I = IN (M = MN) motor speed ω = 0,5 ω. Identify additional resistance Ra.
Figure 1.4 – Electric motor characteristics in relative units.
Figure 1.5 – Electric motor characteristics in relative units.
1.2.6 To calculate analytically and graphically starting rheostat levels and sections support. Build a startup diagram (Fig. 1.6) based on variants of the table 1.7.
1.2.7 To determine the real constants of elevating speed and speed of descend of loaded and empty cart and compare them with a given nominal speed with the help of natural characteristics of the engine (Fig. 1.6). During the defining of speeds identify static moments of resistance reduced to the motor shaft that must be accepted by calculation results in paragraph 1.2.2.
1.2.8 To build a characteristic ω = f (M) for opposition circuit engine braking mode (Fig. 1.6) at conditions when the original braking torque during braking from set speed of loaded cart lift is equal to the value shown in the table. 1.7.
Figure 1.6 – Startup and braking diagrams.
1.2.9 To define dynamic braking resistance Rdn for the dynamic braking mode of direct current motor during descending of loaded cart with speed ω= 0.3ωN (Fig. 1.6).
1.2.10 Make a circuit diagram of electric drive taking into account starting and braking resistances (Fig. 1.7,1.8) Note. Do not perform for variants with AC motors i.1.2.9 .
Table 1.7 – Initial data in variants.
Variant number |
Motor type |
Performance accord to speed of rotating |
Amount of starting ratio |
Order of the maximal moment |
|
At startup КП=Мі/Мн |
At braking Кт=Мт.і/Мн |
||||
1 |
Д32 |
Low-speed |
3 |
2,5| |
2 |
2 |
МТН311-6 |
- |
3 |
2 |
2 |
3 |
Д32 |
Rapid |
3 |
2,5 |
1,8 |
4 |
МТН312-6 |
- |
3 |
2 |
1.8 |
5 |
Д41 |
Low-speed |
3 |
2,5 |
1.4 |
6 |
МТН411-6 |
- |
3 |
2 |
1.4 |
7 |
Д41 |
Rapid |
4 |
2,5 |
1,6 |
8 |
МТН412-6 |
- |
3 |
2 |
1,6 |
9 |
Д806 |
Low-speed |
3 |
2 |
1,8 |
10 |
МТН312-8 |
- |
3 |
2 |
1,8 |
11 |
Д806 |
Rapid |
5 |
2 |
2 |
12 |
МТН411-8 |
- |
4 |
2 |
2 |
13 |
Д808 |
Low-speed |
3 |
2,5 |
1,4 |
14 |
МТН412-8 |
- |
4 |
2 |
1,6 |
15 |
Д808 |
Rapid |
5 |
2 |
1,8 |
16 |
МТН511-8 |
- |
4 |
2 |
2 |
17 |
Д32 |
Low-speed |
4 |
2 |
1,6 |
18 |
МТН311-6 |
- |
4 |
2 |
1,8 |
19 |
Д32 |
Rapid |
4 |
2,5 |
1,4 |
20 |
МТН312-6 |
- |
4 |
2 |
2 |
21 |
Д41 |
Low-speed |
4 |
2 |
1,8 |
22 |
МТН411-6 |
- |
4 |
2 |
1,6 |
23 |
Д41 |
Rapid |
4 |
3 |
2 |
24 |
МТН412-6 |
- |
4 |
2 |
1,8 |
25 |
Д808 |
Low-speed |
4 |
2 |
1,8 |
Extension of the table 1.7.
Variant number |
Motor type |
Performance accord to speed of rotating |
Amount of starting ratio |
Order of the maximal moment |
|
At startup КП=Мі/Мн |
At braking Кт=Мт.і/Мн |
||||
26 |
Д32 |
Low-speed |
3 |
2,5| |
2 |
27 |
МТН311-6 |
- |
3 |
2 |
2 |
28 |
Д32 |
Rapid |
3 |
2,5 |
1,8 |
29 |
МТН312-6 |
- |
3 |
2 |
1.8 |
30 |
Д41 |
Low-speed |
3 |
2,5 |
1.4 |
31 |
МТН411-6 |
- |
3 |
2 |
1.4 |
32 |
Д41 |
Rapid |
4 |
2,5 |
1,6 |
33 |
МТН412-6 |
- |
3 |
2 |
1,6 |
34 |
Д806 |
Low-speed |
3 |
2 |
1,8 |
35 |
МТН312-8 |
- |
3 |
2 |
1,8 |
36 |
Д806 |
Rapid |
5 |
2 |
2 |
37 |
МТН411-8 |
- |
4 |
2 |
2 |
38 |
Д808 |
Low-speed |
3 |
2,5 |
1,4 |
39 |
МТН412-8 |
- |
4 |
2 |
1,6 |
40 |
Д808 |
Rapid |
5 |
2 |
1,8 |
41 |
МТН511-8 |
- |
4 |
2 |
2 |
42 |
Д32 |
Low-speed |
4 |
2 |
1,6 |
43 |
МТН311-6 |
- |
4 |
2 |
1,8 |
44 |
Д32 |
Rapid |
4 |
2,5 |
1,4 |
45 |
МТН312-6 |
- |
4 |
2 |
2 |
46 |
Д41 |
Low-speed |
4 |
2 |
1,8 |
47 |
МТН411-6 |
- |
4 |
2 |
1,6 |
48 |
Д41 |
Rapid |
4 |
3 |
2 |
49 |
МТН412-6 |
- |
4 |
2 |
1,8 |
50 |
Д808 |
Low-speed |
4 |
2 |
1,8 |
Figure 1.7 – Principal scheme of force part of d.c. electric drive.
Figure 1.8 – Principal scheme of force part of a.c. electric drive.