DE-STA-CO F5-B AC Inverter Drive - Manual (Page 25)

25
On period
d.c.f.
Formulas
4. Braking time with braking resistor
Valid range: n
1
> n
N
(field weakening)
Conditions: T
B
- 1.5 • T
N
f < 1.4 x rated frequency of motor
Conditions: P
B
< P
R
Valid range: n
1
> n
N
f < 1.4 x rated frequency of motor
P
B
< P
R
3. Peak braking power
1. Braking time without braking
resistor 2. Braking torque (required)
(J
M
+ J
L
) • (n
1
- n
2
)
T
B
= - T
L
(307 • t
B)
T
B
• n
1
P
B
=
7.04
(J
M
+ J
L
) • (n
1
- n
2
)
t
Bmin
=
307 • (K • T
N
+ T
L
)
t
f
t
B
t
Z
ON period d.c.f for cycle
time t
Z
> 120 s
ON period d.c.f for cycle
time t
Z
< 120 s
Definitions
(J
M
+ J
L
) • (n
1
- n
2
)
t
Bmin
=
307 • K• T
N
+ T
L
+ ( )
(P
R
• 7.04)
(n
1
- n
2
)
P
R
• 9.55
Conditions: - T
N
• (1.5 -K)
(n
1
- n
2
)
t
B
d.c.f = • 100 %
t
Z
t
B
d.c.f = • 100 %
120 s
K = 0.25 for motors up to 2 hp
0.20 for motors
3 to 5 hp
0.15 for motors 7.5 to15 hp
0.08 for motors 20 to 60 hp
0.05 for motors 75 to 400 hp
J
M
= Moment of inertia of the motor [lb ft 2 ]
J
L
= Moment of inertia of the load [lb ft 2 ]
n
1
= Motor speed before deceleration [rpm]
n
2
= Motor speed after deceleration [rpm]
(Stand still = 0 rpm)
n
N
= Motor rated speed [rpm]
T
N
= Motor rated torque [ft lbs]
T
B
= Braking torque (required) [ft lbs]
T
L
= Load torque [ft lbs]
t
B
= Braking time (required) [s]
t
Bmin
= Minimum braking time [s]
t
Z
= Cycle time [s]
P
B
= Peak braking power [W]
P
R
= Peak power dissipation of the resistor [W]
Installation and Connection