Danfoss VLT Brake Resistor MCE 101 Design Manual page 21

Programming
2-10 Brake Function
Option: Function:
Available selections depend on 1-10 Motor
Construction:
[0] Asynchron:
•
[0] Off
•
[1] Resistor brake
•
[2] AC brake
[1] PM non-salient:
•
[0] Off
•
[1] Resistor brake
[0] Off No brake resistor installed.
[1] Resistor Brake resistor incorporated in the system, for
brake dissipation of surplus brake energy as heat.
Connecting a brake resistor allows a higher DC-
link voltage during braking (generating
operation). The resistor brake function is only
active in frequency converters with an integral
dynamic brake.
[2] AC brake AC Brake only works in Compressor Torque mode
in 1-03 Torque Characteristics.
2-11 Brake Resistor (ohm)
Range: Function:
Set the brake resistor value in Ω. This
Size [ 5.00 -
related 65535.00
value is used for monitoring the power
*
Ohm]
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 [ 0.001 - Parameter 2-12 Brake Power Limit (kW) is
related 2000.000 the expected average power dissipated in
*
kW] 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 =
P is the average power dissipated in
br,avg
the brake resistor, R
the brake resistor. t
breaking time within the 120 s period, T
MG90O202
Design Guide
U br 2 V × t br s
R br Ω × T br s
is the resistance of
br
is the active
br
.
br
Danfoss A/S © Rev. 05/2014 All rights reserved.
2-12 Brake Power Limit (kW)
Range: Function:
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).
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:
•
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 & Warning and trip based on 120 s time
trip 120s periode.
[4] Warning 30s Warning based on 30 s time periode.
[5] Trip 30s Trip based on 30s time periode
is
br
5 5
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