Inductive reactors for the start-up of asynchronous three-phase motors
Limitation of strain on the network and the motor at start-up
Start-up with stator reactance consists in the insertion of three reactors in the line capable of causing a suitable voltage drop at the motor terminals.
This type of start-up has the advantage of its great simplicity and the feature of an easily adjustable start-up, using the various models available.
The downside is that the rotor will impose a limit on the service provided by the motor (the number of start-ups per hour is equal to 4 or 5) and involves a low power factor at start-up.
Start-up with an auto-transformer is based on the same voltage reduction principle; however, auto-transformers are normally used with large machinery having low / medium-level voltages.
MAIN CHARACTERISTICS OF REACTORS FOR THE START-UP OF THREE-PHASE MOTORS
- THESE REACTORS ARE CROSSED BY HIGH CURRENTS OF BRIEF DURATION THAT GENERATE A HIGH STRAY MAGNETIC FIELD, WHICH CAN HEAT UP AND PLACE UNDER STRESS THE SURROUNDING METALLIC PARTS.
- They are sized to create a voltage drop of approximately 30-45% with respect to the nominal value at motor start-up.
- They are sized to create a voltage drop of approximately 30-45% with respect to the nominal value at motor start-up.
- In terms of their construction they are very robust, making it possible for them to withstand the strong electro-dynamic stress caused by motor inrush current.
- Built with materials in classes F and H and impregnated with cementing paint.
- THE INTENDED USE OF THE REACTORS IS FOR 2 CONSECUTIVE STARTS AND FOUR STARTS/HR OF ABOUT 10-15 SECONDS.
- BESIDES THE POWER OF THE MOTOR TO BE CONTROLLED, WHEN AN ORDER IS PLACED THE CLIENT MUST ALSO SPECIFY OPERATING VOLTAGE AND FREQUENCY.
The table below provides indicative dimensions (mm) of the most common types of reactors that we have standardized.
|
TYPE |
HP motor |
A |
B |
C |
D |
E |
G |
Kg. |
|
RP0.1 |
2—3 |
120 |
57 |
115 |
100 |
46 |
67 |
2 |
|
RP0.2 |
4—6 |
150 |
78 |
147 |
125 |
56 |
82 |
4 |
|
RP0.3 |
7—10 |
150 |
93 |
147 |
125 |
71 |
97 |
5,4 |
|
RP0.4 |
11—15 |
150 |
93 |
147 |
125 |
71 |
97 |
5,8 |
|
RP0.5 |
16—22 |
180 |
100 |
180 |
150 |
76 |
106 |
7,4 |
|
RP1 |
23—29 |
180 |
100 |
185 |
150 |
76 |
108 |
8,4 |
|
RP1.5 |
30—37 |
180 |
106 |
195 |
150 |
86 |
130 |
10,9 |
|
RP2 |
40—50 |
240 |
120 |
235 |
200 |
90 |
130 |
16,8 |
|
RP2.2 |
50—60 |
240 |
132 |
240 |
200 |
100 |
142 |
20,5 |
|
RP2.5 |
60—70 |
300 |
130 |
290 |
250 |
92 |
130 |
23,8 |
|
RP3 |
80—100 |
300 |
140 |
290 |
250 |
102 |
166 |
31 |
|
RP3.5 |
110—120 |
300 |
150 |
300 |
250 |
112 |
190 |
37 |
|
RP4 |
130—150 |
300 |
160 |
300 |
250 |
122 |
220 |
42 |
|
RP5 |
160—180 |
360 |
175 |
355 |
325 |
140 |
220 |
55 |
|
RP6 |
200—220 |
360 |
190 |
350 |
325 |
155 |
240 |
68 |
|
RP7 |
250—280 |
360 |
210 |
350 |
325 |
185 |
290 |
89 |
NOTES: SIZES ARE PURELY INDICATIVE AND MAY BE MODIFIED WITHOUT PRIOR NOTICE
