Powtran PB200 Series, Руководство по эксплуатации

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14
Chapter 5 Brake unit and brake resistor
5-1 Brake unit
5-1-1.Brake voltage selection is based on below two conditions:
(1) According to the input voltage level of inverter , choose the brake unit with relative
voltage level
(2) According to the required braking power when inverter is braking , choose the brake
unit with relative power .
The principle of brake unit power selection is that the power of brake unit is greater than the
braking power . in the case where the braking power is not specified , please estimate according to
below ways :
Pb=P*Td*K
In this formula:Pb-----braking power;
P----- motor power
K----- mechanical energy conversion efficiency,the general value is 0.7
Td---- ratio of brake torque to motor rated torque
Td values vary in different systems , as shown in the following table.
Common
applications
Elevator lift
crane
Uncoiler and
recoiling
Large inertia equipment
that requires quick
stopping
Ordinary
inertial load
Td value 100% 120% 120% 80%
5-1-2.Brake resistor resistance selection
When it is braking, the regenerative energy of the motor is almost consumed on the brake
resistor ,according to the formula:
U*U/R=Pb
In the formula:U----- braking voltage in stable braking system
(vary in different systems , for 220VAC system usually choose 380v; for 380VAC system
usually choose 700V, for 480VAC system usually choose 800V)
Note: when the value of R is less than the minimum resistance of each voltage level, multiple
brake units are required.
5-1-3.Brake unit power selection
In theory , the power of brake resistance is same as the braking power , but considering
derating is 70%. according to formula:
0.7*Pr=Pb*ED
In the formula:Pr-----brake unit power
ED----- braking frequency , the proportion of braking process in the whole working process
Common application ED value
Uncoiler and recoiling
20%
～
30%
Accidental braking load 5%
Elevator 20%
～
30%
Lifting machinery , centrifuge 50%
～
60%
Injection molding machine 5%
～
10%
General occasion 10%
In the above table, the recommended braking unit and braking resistor resistance can meet
various inverters with ED=0
～
100%. And the power of the braking resistor depends on the
application conditions.