Danfoss VLT Brake Resistor MCE 101 Design Manual page 24

Programming
2-11 Brake Resistor (ohm)
Range:
Size [ 5.00 -
related 65535.00
*
Ohm]
5 5
2-12 Brake Power Limit (kW)
Range:
Size [ 0.001 -
related 2000.000
*
kW]
2-13 Brake Power Monitoring
Option:
22
Design Guide
Function:
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).
Function:
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.
U br 2 V × t br s
P br,avg W =
R br Ω × T br s
P is the average power dissipated in
br,avg
the brake resistor, R is the resistance of
br
the brake resistor. t is the active
br
breaking time within the 120 s period, T
U is the DC voltage where the brake
br
resistor is active.
NOTICE
If values are unknown, or if T
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).
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:
Danfoss A/S © Rev. 05/2014 All rights reserved.
2-13 Brake Power Monitoring
Option:
[0] Disabled
*
[1] Warning 120s Warning based on 120 s time periode.
[2] Trip 120s
[3] Warning &
trip 120s
[4] Warning 30s
[5] Trip 30s
.
br
[6] Warning &
trip 30s
[7] Warning 60s
[8] Trip 60s
[9] Warning &
is
br
trip 60s
[10] Warning 300s Warning based on 300 s time periode.
[11] Trip 300s
[12] Warning &
trip 300s
[13] Warning 600s Warning based on 600s time periode.
[14] Trip 600s
[15] Warning &
trip 600s
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%).
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.
Brake power monitoring disabled.
Trip based on 120 s time periode.
Warning and trip based on 120 s time
periode.
Warning based on 30 s time periode.
Trip based on 30s time periode
Warning and trip based on 30 s time
periode.
Warning based on 60 s time periode.
Trip based on 60 s time periode.
Warning and trip based on 60 s time
periode.
Trip based on 300 s time periode.
Warning and trip based on 300 s time
periode.
Trip based on 600 s time periode.
Warning and trip based on 600 s time
periode.
MG90O202