Danfoss VLT 380-500 V Design Manual page 126

Braking
Brake power levels
The following brake power levels apply to the VLT
Drive Modules.
Power size
kW (hp)
®
VLT HVAC Drive FC 102 and VLT
(380–480 V)
315
(450)
355–1000
(500–1350)
®
VLT HVAC Drive FC 102 and VLT
(525–690 V)
315–355
(450–500)
400–1200
(400–1350)
®
VLT AutomationDrive FC 302 (380–480 V)
250
(350)
315–800
(450–1200)
®
VLT AutomationDrive FC 302 (525–690 V)
250–315
(300–350)
355–1000
(450–1150)
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
13 13 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:
2
U
dc
R Ω =
br P
peak
where
P =P xM
peak motor
Brake resistance depends on the DC-link voltage (U
Voltage Brake active
380–480 V 769 V
525–690 V 1084 V
Table 13.2 Brake Limits for VLT
124
Cycle Braking duty cycle Braking duty cycle
time (s) at 100% torque
®
AQUA Drive FC 202
600 Continuous
600 40%
®
AQUA Drive FC 202
600 Continuous
600 40%
600 Continuous
600 40%
600 Continuous
600 40%
[%]xη xη [W]
br motor VLT
Warning before cut
out
810 V
1109 V
®
HVAC Drive FC 102 and
Danfoss A/S © 6/2016 All rights reserved.
®
VLT Parallel Drive Modules
®
VLT AQUA Drive FC 202 Parallel Drive Modules
®
Parallel
Voltage
at over torque 380–500 V 795 V
(150%)
525–690 V 1084 V
Table 13.3 Brake Limits for VLT
Parallel Drive Modules
10%
NOTICE
10%
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.
10%
Danfoss recommends the brake resistance R
R formula guarantees that the frequency converter is
10%
rec
able to brake at the highest brake power (M
The formula can be written as:
10%
R Ω =
rec
10%
η is typically at 0.90
motor
η is typically at 0.98
VLT
10%
For 480 V, 500 V, and 600 V frequency converters, R
160% brake power is written as:
10%
500V : R
rec
600V : R
rec
690V : R
rec
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
).
dc
Brake resistors can get hot while/after braking and must
be placed in a secure environment to avoid fire risk.
Cut out
(trip)
820 V
1130 V
Brake active Warning before cut
out
828 V
1109 V
®
AutomationDrive FC 302
2
U x 100
dc
P x M xη x η
motor ( % ) VLT motor
br
464923
= Ω
P
motor
630137
= Ω
P
motor
832664
= Ω
P
motor
Cut out
(trip)
855 V
1130 V
. Using the
rec
) of 160%).
br(%)
at
rec
MG37N102