Dimensioning Example @ 575 V - gefran BUy-1020 Manuel D'utilisation

The peak braking power is given by
P = (J * n * ∆ω * 2Π) / (t
PBR TOT 1
I = P / V = 9700 / 753 = 12.9A
PBR PBR BR
R ≤ V / I = 753 / 12.9 = 58.3 Ω
BR BR PBR
Being I = 12.9A, the BUy-1020 unit meets the requirements.
PBR
Resistor choice
The ohmic value must be between the minimum allowed by BUy and 58 Ω.
The resistor rated power must be:
P = (P / 2 ) * (t
NBR PBR
The resistor rated power is low because of the low duty cycle (10 / 20) but the resistor must
be in a position to bear the energy applied during the 10-second braking process. This energy
corresponds to 43740 Joules. In the table of the standard braking resistors (chapter 6) it is
possible to notice how the model RFPD 900 DT 68R has a sufficient rated power value and
a too low E value (21kWsec/ 21000 Joules).
BR
As a consequence the chosen model is RFPD 1100 DT 40R whose E
/ 44000Joules.

4.2 Dimensioning example @ 575 V

(For AVy/AGy-EV only)
Data:
- Mains voltage
- Motor efficiency
- Motor rated power
- Motor rated speed
- Moment of inertia of the motor
- Moment of inertia loading the motor shaft
- Friction of the system
- Initial braking speed
- Final braking speed
- Braking time
- Cycle time
Total moment of inertia:
J = J + J = 35 + 3.1 = 38.1 kgm2
TOT M L
∆ω = [2Π * (n - n )] / 60 sec/min = 2Π * 1700 / 60 = 178 sec
1 2
55-GB
* 60) = 9.7 kW
BR
/ T) = (9700 / 2 ) * (10 / 120) = 404 W
BR
—————— Braking Unit ——————
therefore
and
(%)
(P )
M
(n )
n
(J )
M
(J )
L
(M )
S
(n )
1
(n )
2
(t )
BR
(T)
and
-1
value is 44kWsec
BR
3 x 575 V
95
150 HP or 104 kW
1785 rpm
3.1 kgm
2
35 kgm
2
10% of the rated torque
1700 rpm
0 rpm
10 sec
120 sec