Lenze 9400 Manual de usuario descargar pdf (Pagina 269)

Lenze · Servo-Inverter 9400 HighLine · Reference manual · DMS 10.0 EN · 11/2013 · TD05/06 269

7Braking operation

7.2 Monitoring

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

7.2.2 Ixt utilisation - brake transistor

The controller is provided with a monitoring function for the Ixt utilisation of the internal brake

transistor.

[7-1] Signal flow of Ixt utilisation - brake chopper

• Monitoring is based on a mathematical model which calculates the braking current from the

current DC-bus voltage and the brake resistance parameterised.

• Hence, monitoring can be activated although no brake resistor is connected and can

therefore also be used for a testing mode to check the parameterisation.

• During the calculation the thermal utilisation of the brake transistor is taken into consideration

by the use of an accordingly adapted time constant.

•In C00133

it can be selected whether the minimum brake resistance (display inC00134) which

depends on the network setting in C00173

) or the brake resistor 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

integrated 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 time period depending on the device.

• The calculated utilisation is provided as 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

, "Brake chopper: Ixt >

C00570" is entered in the logbook and the response set in C00569

(default setting: "Warning")

is activated.

• When the utilisation reaches the limit value (100 %):

• The activation of the brake chopper is reset to the permanently permissible mark-to space

ratio (taking the parameterised brake resistance into consideration). (The brake chopper is

activated with 4 kHz, which means that it can be switched on/off at minimum intervals of

250 μs.)

• The response set in C00573

(default setting: "No response") is activated with the

corresponding effects on the state machine and the inverter.

 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 transistor: Ixt overload

U

DC_act

U

DC_act

I=

Br

I=

Br

I

Br

= f(duty cycle, R )

Br

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