Lenze E94ARNE Regenerative power supply - Manual (Page 26)

9400 regenerative power supply module | Parameter setting
Regenerative power supply module application
Parameterising the brake chopper/brake resistor
26
L
EDS94ARNExxxx EN 2.3 - 06/2014
3.1.3.2 Ixt utilisation of brake transistor
The regenerative power supply module monitors the Ixt utilisation of the internal brake
transistor.
[3-1] Signal flow of Ixt utilisation - brake chopper
 The monitoring function is based on a mathematical model which calculates the
braking current from the current DC-bus voltage and the brake resistance
parameterised.
– Hence, the monitoring function can respond even if no brake resistor is connected
and can therefore also be used for a testing mode to check the parameterisation.
 The calculation considers the thermal utilisation of the brake transistor by a
correspondingly adapted time constant.
 Use C00133 to select whether the minimum brake resistance depending on the mains
setting in C00173 (display in C00134 ), or the brake resistance value parameterised in
C00129 is to be used as a reference for calculating the utilisation.
 C00137 displays the calculated utilisation of the brake transistor in [%].
– A 100 % utilisation corresponds to the continuous braking power which is provided
by the brake chopper at a DC-bus voltage of 790 V (or 390 V at a mains voltage of
230 V).
– The maximum braking power (assuming that the utilisation starts at 0 %) can be
provided for a period depending on the device.
– The calculated utilisation is also provided as the oscilloscope signal
Common.dnIxtBrakeChopper to check the braking operation while the system is
running
(scaling: 2
30 ≡ 100 %).
 If the utilisation exceeds the advance warning threshold set in C00570 , the message
"Brake chopper: Ixt > C00570" is entered into the logbook and the response set in
C00569 (default setting: "Warning") is activated.

Note!
The braking operation will never be switched off by this monitoring function.
Ixt
C00137
1
0
C00134
C00129
C00133
T = 0
Off
T = 1
On
100 %
C00570
C00569
C00573
Logbook entry "Brake chopper: Ixt > C00570"
Logbook entry " " Brake chopper: Ixt overload
U
DC_act
U
DC_act
I =
Br
I =
Br
I
Br
= f(duty cycle, R )
Br