2-11 Brake Resistor (ohm)
Range: Function:
Size
related*
[ 5.00 -
65535.00
Ohm]
Set the brake resistor value in Ω. This
value is used for monitoring the power
to the brake resistor in 2-13 Brake Power
Monitoring. This parameter is only active
in frequency converters with an integral
dynamic brake.
Use this parameter for values without
decimals. For a selection with 2 decimals,
use parameter 30-81 Brake Resistor (ohm).
2-12 Brake Power Limit (kW)
Range: Function:
Size
related*
[ 0.001 -
2000.000
kW]
Parameter 2-12 Brake Power Limit (kW) is
the expected average power dissipated in
the brake resistor over the time period
selected within 2-13 Brake Power
Monitoring. It is used as the monitoring
limit for 16-33 Brake Energy /2 min and
thereby specifies when a warning/alarm is
to be given.
To calculate parameter 2-12 Brake Power
Limit (kW), the following formula can be
used.
P
br,avg
W
=
U
br
2
V
×
t
br
s
R
br
Ω
×
T
br
s
P
br,avg
is the average power dissipated in
the brake resistor, R
br
is the resistance of
the brake resistor. t
br
is the active
breaking time within the 120 s period, T
br
.
U
br
is the DC voltage where the brake
resistor is active.
NOTICE
If values are unknown, or if T
br
is
different from 120 s, the practical
approach is to run the brake
application, readout 16-33 Brake
Energy /2 min and then enter this
+20% in 2-12 Brake Power Limit
(kW).
2-13 Brake Power Monitoring
Option: Function:
This parameter is only active in frequency
converters with an integral dynamic brake.
This parameter enables monitoring of the
power to the brake resistor. The power is
calculated on the basis of the resistance
(parameter 2-11 Brake Resistor (ohm)), the
DC-link voltage, and the resistor duty time.
The time periode can be selected in this
parameter.
The functions are as follows:
2-13 Brake Power Monitoring
Option: Function:
•
Off:
Brake power monitoring disabled.
Default setting.
•
Warning (time period):
Activates a warning on the display
when the power transmitted over
the selected time period exceeds
100% of the monitoring limit
(parameter 2-12 Brake Power Limit
(kW)). The warning disappears
when the transmitted power falls
below 80% of the monitoring limit.
•
Trip (time period);
Trips frequency converter and
displays an alarm when the
calculated power exceeds 100% of
the monitoring limit.
•
Warning & trip (time period):
Activates both of the above,
including warning, trip and alarm.
[0] * Disabled Brake power monitoring disabled.
[1] Warning 120s Warning based on 120 s time periode.
[2] Trip 120s Trip based on 120 s time periode.
[3] Warning &
trip 120s
Warning and trip based on 120 s time
periode.
[4] Warning 30s Warning based on 30 s time periode.
[5] Trip 30s Trip based on 30s time periode
[6] Warning &
trip 30s
Warning and trip based on 30 s time
periode.
[7] Warning 60s Warning based on 60 s time periode.
[8] Trip 60s Trip based on 60 s time periode.
[9] Warning &
trip 60s
Warning and trip based on 60 s time
periode.
[10] Warning 300s Warning based on 300 s time periode.
[11] Trip 300s Trip based on 300 s time periode.
[12] Warning &
trip 300s
Warning and trip based on 300 s time
periode.
[13] Warning 600s Warning based on 600s time periode.
[14] Trip 600s Trip based on 600 s time periode.
[15] Warning &
trip 600s
Warning and trip based on 600 s time
periode.
If power monitoring is disabled or Warning is selected, the
brake function remains active, even if the monitoring limit
is exceeded. This may lead to thermal overload of the
resistor. It is also possible to generate a warning via a
relay/digital outputs. The measuring accuracy of the power
monitoring depends on the accuracy of the resistance of
the resistor (better than ±20%).
Programming
Design Guide
22 Danfoss A/S © Rev. 05/2014 All rights reserved. MG90O202
55
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