GE AF-650 GP - Page 167

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If power monitoring is set to Off [0] or Warning [1], 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%).

B-15 Brake Check

Option: Function:

Select type of test and monitoring function to check the connection to the brake resistor, or whether a

brake resistor is present, and then display a warning or an alarm in the event of a fault.

NB!

The brake resistor disconnection function is tested during power-up. However the brake IGBT test is

performed when there is no braking. A warning or trip disconnects the brake function.

The testing sequence is as follows:

1. The DC link ripple amplitude is measured for 300 ms without braking.

2. The DC link ripple amplitude is measured for 300 ms with the brake turned on.

3. If the DC link ripple amplitude while braking is lower than the DC link ripple amplitude before

braking + 1 %: Brake check has failed by returning a warning or alarm.

4. If the DC link ripple amplitude while braking is higher than the DC link ripple amplitude before

braking + 1 %: Brake check is OK.

[0] * Off Monitors brake resistor and brake IGBT for a short-circuit during operation. If a short-circuit occurs,

warning 25 appears.

[1] Warning Monitors brake resistor and brake IGBT for a short-circuit, and runs a test for brake resistor disconnection

during power-up.

[2] Trip Monitors for a short-circuit or disconnection of the brake resistor, or a short-circuit of the brake IGBT. If

a fault occurs, the frequency converter cuts out while displaying an alarm (trip locked).

[3] Stop and trip Monitors for a short-circuit or disconnection of the brake resistor, or a short-circuit of the brake IGBT. If

a fault occurs, the frequency converter ramps down to coast and then trips. A trip lock alarm is displayed

(e.g. warning 25, 27 or 28).

[4] AC brake Monitors for a short-circuit or disconnection of the brake resistor, or a short-circuit of the brake IGBT. If

a fault occurs, the frequency converter performs a controlled ramp down.

NB!

Remove a warning arising in connection with Off [0] or Warning [1] by cycling the mains supply. The fault must be corrected first. For Off [0] or Warning [1], the

frequency converter keeps running even if a fault is located.

This parameter is only active in frequency converters with an integral dynamic brake.

B-16 AC brake Max. Current

Range: Function:

100.0 %* [0.0 - 1000.0 %] Enter the maximum permissible current when using AC brake to avoid overheating of motor windings.

B-17 Over-voltage Control

Option: Function:

Over-voltage control (OVC) reduces the risk of the frequency converter tripping due to an over voltage on

the DC link caused by generative power from the load.

[0] * Disabled No OVC required.

[1] Enabled (not at stop) Activates OVC except when using a stop signal to stop the frequency converter.

[2] Enabled Activates OVC.