Brake power levels
The following brake power levels apply to the VLT
®
Parallel
Drive Modules.
Power size
kW (hp)
Cycle
time (s)
Braking duty cycle
at 100% torque
Braking duty cycle
at over torque
(150%)
VLT
®
HVAC Drive FC 102 and VLT
®
AQUA Drive FC 202
(380–480 V)
315
(450)
600
Continuous
10%
355–1000
(500–1350)
600
40%
10%
VLT
®
HVAC Drive FC 102 and VLT
®
AQUA Drive FC 202
(525–690 V)
315–355
(450–500)
600
Continuous
10%
400–1200
(400–1350)
600
40%
10%
VLT
®
AutomationDrive FC 302 (380–480 V)
250
(350)
600
Continuous
10%
315–800
(450–1200)
600
40%
10%
VLT
®
AutomationDrive FC 302 (525–690 V)
250–315
(300–350)
600
Continuous
10%
355–1000
(450–1150)
600
40%
10%
Table 13.1 Brake Cycle for Parallel Drive Modules
Danfoss offers brake resistors with duty cycle of 5%, 10%,
and 40%. If a 10% duty cycle is applied, the brake resistors
are able to absorb brake power for 10% of the cycle time.
The remaining 90% of the cycle time is used on dissipating
excess heat.
Make sure that the resistor is designed to handle the
required braking time. The maximum allowable load on
the brake resistor is stated as a peak power at a given
intermittent duty cycle. The brake resistance is calculated:
R
br
Ω =
U
dc
2
P
peak
where
P
peak
=P
motor
xM
br
[%]xη
motor
xη
VLT
[W]
Brake resistance depends on the DC-link voltage (U
dc
).
Voltage
Brake active
Warning before cut
out
Cut out
(trip)
380–480 V 769 V
810 V
820 V
525–690 V 1084 V
1109 V
1130 V
Table 13.2 Brake Limits for VLT
®
HVAC Drive FC 102 and
VLT
®
AQUA Drive FC 202 Parallel Drive Modules
Voltage
Brake active
Warning before cut
out
Cut out
(trip)
380–500 V 795 V
828 V
855 V
525–690 V 1084 V
1109 V
1130 V
Table 13.3 Brake Limits for VLT
®
AutomationDrive FC 302
Parallel Drive Modules
NOTICE
Check that the brake resistor can handle a voltage of 410
V, 820 V, 850 V, 975 V, or 1130 V - unless Danfoss brake
resistors are used.
Danfoss recommends the brake resistance R
rec
. Using the
R
rec
formula guarantees that the frequency converter is
able to brake at the highest brake power (M
br(%)
) of 160%).
The formula can be written as:
R
rec
Ω =
U
dc
2
x 100
P
motor
x M
br
( % )
xη
VLT
x η
motor
η
motor
is typically at 0.90
η
VLT
is typically at 0.98
For 480 V, 500 V, and 600 V frequency converters, R
rec
at
160% brake power is written as:
500V : R
rec
= 464923
P
motor
Ω
600V : R
rec
= 630137
P
motor
Ω
690V : R
rec
= 832664
P
motor
Ω
NOTICE
Do not select a resistor brake circuit resistance that is
higher than what is recommended by Danfoss. 1 brake
resistor per brake chopper.
NOTICE
If a short circuit occurs in the brake transistor, power
dissipation in the brake resistor is only prevented by
using a mains switch or contactor to disconnect the
mains from the frequency converter. The frequency
converter can control the contactor.
WARNING
FIRE HAZARD
Brake resistors can get hot while/after braking and must
be placed in a secure environment to avoid fire risk.
Braking
VLT
®
Parallel Drive Modules
124
Danfoss A/S © 6/2016 All rights reserved.
MG37N102
13
13
Summary of Contents for VLT 380-500 V
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