Efficient Networks S120 manual 177

Vector V/f control (r0108.2 = 0) 5.4 Vdc control

In the event of a power failure, Vdc_min control is activated when the Vdc_min switch-in level is undershot. This controls the DC link voltage and maintains it at a constant level. The motor speed is reduced.

When the power supply is restored, the DC link voltage increases again and Vdc_min control is deactivated at 5 % above the Vdc_min switch-on level. The motor continues operating normally.

If the power supply is not reestablished, the motor speed continues to drop. When the threshold in p1297 is reached, this results in a response in accordance with p1296.

Once the time threshold (p1295) has elapsed without the line voltage being reestablished, a fault is triggered (F07406), which can be parameterized as required (factory setting: OFF3).

The Vdc_min controller can be activated for a drive. Other drives can participate in supporting the DC link, by transferring a scaling of their speed setpoint from the controlling drive via BICO interconnection.

Note

You must make sure that the converter is not disconnected from the power supply. It could become disconnected, for example, if the line contactor drops out. The line contactor should have an uninterruptible power supply (UPS), for example.

Description of Vdc_max control

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Figure 5-8 Switching Vdc_max control on/off

The switch-in level for Vdc_max control (r1282) is calculated as follows:

●When the function for automatically detecting the switch-on level is switched off (p1294 = 0)

r1282 = 1.15 * p0210 (device connection voltage, DC link).

●When the function for automatically detecting the switch-on level is switched on (p1294 = 1)

r1282 = Vdc_max - 50 V (Vdc_max: overvoltage threshold of the Motor Module)

Drive Functions	177
Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4