GE AF-650 GP Programming Manual page 147

Parameter Descriptions
B-10 Brake Function
Option:
[2] AC brake Is selected to improve braking without using a
3 3
B-11 Brake Resistor (ohm)
Range:
50.00 [5.00 -
Ohm 65535.00
*
Ohm]
B-12 Brake Power Limit (kW)
Range:
5.000 [0.001 -
kW 2000.000
*
kW]
146
Function:
brake resistor. This parameter controls an
overmagnetisation of the motor when running
with a generatoric load. This function can
improve the OVC-function. Increasing the
electrical losses in the motor allows the OVC
function to increase the braking torque without
exceeding the overvoltage limit.
NOTICE
The AC brake is not as efficient as
dynamic braking with resistor.
+
AC brake is for VVC mode in both open
and closed loop.
Function:
Set the brake resistor value in Ω. This value
is used for monitoring the power to the
brake resistor in parameter B-13 Braking
Thermal Overload. 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 B-11 Brake Resistor (ohm).
Function:
Parameter B-12 Brake Power Limit (kW) is the
expected average power dissipated in the
brake resistor over a period of 120 s. It is
used as the monitoring limit for
parameter DR-33 Brake Energy Average and
thereby specifies when a warning/alarm is
to be given.
To calculate parameter B-12 Brake Power
Limit (kW), the following formula can be
used.
2
U V × t s
br br
P W =
br, avg R Ω × T s
br br
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 breaking
br
time within the 120 s period, T
U is the DC voltage where the brake
br
resistor is active. This depends on the unit
as follows:
200–240 V: 390 V
380–500 V: 810 V
525–600 V: 943 V
525–690 V: 1099 V
B-12 Brake Power Limit (kW)
Range:
B-13 Braking Thermal Overload
Option:
[0] Off
*
[1] Warning
[2] Trip
[3] Warning
and trip
[4] Warning
30s
If power monitoring is set to [0] Off or [1] Warning, 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 output. The measuring accuracy of the power
monitoring depends on the accuracy of the resistance of
the resistor (better than ±20%).
.
br
B-15 Brake Check
Option:
02/2016 All rights reserved.
Function:
NOTICE
If R is not known, or if T
br
different from 120 s, the practical
approach is to run the brake
application, readout
parameter DR-33 Brake Energy Average
and then enter this
+ 20% in parameter B-12 Brake Power
Limit (kW).
Function:
This parameter is only active in frequency
converters with a brake.
This parameter enables monitoring of the
power to the brake resistor. The power is
calculated based on the resistance
(parameter B-11 Brake Resistor (ohm)), the DC-
link voltage, and the resistor duty time.
No brake power monitoring required.
Activates a warning on the display when the
power transmitted during the duty time
exceeds 100% of the monitoring limit
(parameter B-12 Brake Power Limit (kW).
The warning disappears when the transmitted
power drops below 80% of the monitoring
limit.
Trips the frequency converter and displays an
alarm when the calculated power exceeds 100%
of the monitoring limit.
Activates both of the above, including warning,
trip, and alarm.
Function:
Parameter B-15 Brake Check is only active in
frequency converters with an integral dynamic
brake.
Select type of test and monitoring function to
check the connection to the brake resistor, or
is
br
DET-618D