|  the
tri phase autotransformer
M.R. Severo developed
the starting auto-transformer characteristics for
electrial motors from 5 HP.
During the starting process of a induction motor,
superior currents move in their coilings at the nominal
current of this motor. That can provoke strong problems
of tension fall in the feeding net. In these cases
it´s recommendable that the motor starting be
in a reduced tension, using for that reason a starting
autotransformer. It has normally taps of 65% and 80%,
employed in motors which start carring light and
heavy cargoes, respectively.
The beginning of the operation
is what appears in the picture 1, in others words,
the starter current which circulate
in the net is reduced in the same relation of the
square of the tap.
The censor of temperature
It´s a device being able to protect the autotransformer
against over charge.
It has a contact which must be placed in series with
the protection contact of the motor thermic relay.
The temperature of its coiling doesn´t reach
130º in a normal operation of the autotrasformer.
In this case, the contact of the sensor of the temperature
is closed. If there is a power charge, the temperature
of the coiling exceeds 130º C, opening the contact
of the sensor proviking the disjunction of the motor.
When the temperature of the coiling come back to its
operation nominal value, the contact of the sensor
will close, permitting a new start of the motor.
Other specifications
According to consultation, we make autotransformers
with taps in the tensions of 50%, 65% and 80%, with
other tensions, duration of the work time, protected
bobbins with sash, etc.
Characteristics:
| • Assayed individually; |
| •
Measurement of the way out tensions in the taps
with applied nominal tension; |
| • Essay in unloaded
for the determination of the consumed current
and damages; |
| •
Conexion using bicromatic screws. |
Technical informations:
Power
|
From 5 HP |
Tensions
|
220/380 or
440V |
Number of start/hour
|
5/10 or 20 starters |
Work
Time
|
15 seconds |
Taps
|
65% and 80% of the nominal tension |
Frequency
|
50 or 60 Hz |
Temperature class
|
"B" (130ºC) |
Isolation Tension
|
0,6 KV |
Protection grade
|
IP - 00 |
Ambient temperature
|
Maximum 45ºC,
minimum - 10ºC |
Limit of elevation
of temperature in the coiling
|
80ºC |
|
Tension applied at industrial frequence |
2.5 KV effective |
| Over tension Limit |
10% above detailed, maintained
the nominal current in the coils |
| Altitude |
Up to 1000m above the sea level |
Dimension of Autotransformer of strater:
|
HP |
Height
(a) |
Width
(b) |
Depth(c)
|
Weight |
|
|
mm |
mm |
mm |
KG |
| 5 |
160 |
215 |
120 |
8 |
|
10 |
160 |
215 |
120 |
8 |
| 12,5 |
210 |
215 |
140 |
10 |
|
15 |
210 |
265 |
130 |
15 |
| 20 |
210 |
265 |
130 |
15 |
|
25 |
210 |
265 |
130 |
15 |
| 30 |
210 |
265 |
140 |
18 |
|
40 |
265 |
265 |
155 |
23 |
| 50 |
265 |
345 |
160 |
30 |
|
60 |
290 |
345 |
160 |
30 |
| 75 |
290 |
345 |
165 |
36 |
|
100 |
315 |
345 |
180 |
42 |
| 125 |
315 |
415 |
205 |
56 |
|
150 |
315 |
415 |
205 |
56 |
| 175 |
315 |
415 |
240 |
75 |
|
200 |
417 |
415 |
240 |
85 |
| 250 |
417 |
460 |
280 |
115 |
|
300 |
417 |
460 |
280 |
115 |
| 350 |
417 |
460 |
280 |
120 |
|
400 |
417 |
460 |
280 |
120 |
| 450 |
417 |
460 |
290 |
141 |
|
500 |
417 |
460 |
290 |
141 |
|
