Vacon 100 hvac Applications Manual

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Vacon 100 hvac Applications Manual Manual pdf 145 page image

9.7 PROTECTIONSP3.9.2 RESPONSE TO EXTERNAL FAULT (ID701)With this parameter, you can set the response of the drive to an external fault. If a faultoccurs, the drive can show a notification of it on the display of the drive. The notification ismade with a digital input. The default digital input is DI3. You can also program the responsedata into a relay output.9.7.1 MOTOR THERMAL PROTECTIONSThe motor thermal protection prevents the motor from becoming too hot.The AC drive can supply a current that is higher than the nominal current. The high currentcan be necessary to the load, and it must be used. In these conditions, there is a risk of athermal overload. Low frequencies have a higher risk. At low frequencies, the cooling effectand the capacity of the motor decrease. If the motor has an external fan, the load reductionat low frequencies is small.The motor thermal protection is based on calculations. The protection function uses theoutput current of the drive to know what is the load on the motor. If the control board is notenergised, the calculations are reset.To adjust the thermal protection of the motor, use the parameters from P3.9.6 to P3.9.10.The thermal current IT tells the load current above which the motor is overloaded. Thiscurrent limit is a function of the output frequency.NOTE!If you use long motor cables (max. 100 m) with small drives (≤1.5 kW), the motorcurrent that the drive measures can be much higher than the actual motor current.It is because there are capacitive currents in the motor cable.CAUTION!Make sure that the airflow to the motor is not blocked. If the airflow is blocked, thefunction does not protect the motor, and the motor can become too hot. This cancause damage to the motor.P3.9.8 MOTOR THERMAL ZERO SPEED COOLING (ID706)When the speed is 0, this function calculates the cooling factor in relation to the point wherethe motor operates at a nominal speed without external cooling.The default value is set for conditions where there is no external fan. If you use an externalfan, you can set the value higher than without the fan, for example at 90%.If you change parameter P3.1.1.4 (Motor Nominal Current), parameter P3.9.2.3 isautomatically set to its default value.Although you change this parameter, it does not have an effect on the maximum outputcurrent of the drive. Only parameter P3.1.1.7 Motor Current Limit can change the maximumoutput current.PARAMETER DESCRIPTIONS VACON · 14524-HOUR SUPPORT +358 (0)201 212 575 · EMAIL: VACON@VACON.COM 9