ABB Electrical 1SCA022747R6490 OT400U03 Switch Disconnector

Model Type: OT400U03 Electrical 1SCA022747R6490 OT400U03 Switch Disconnector

As a rule of thumb, for two cold starts or one hot start, the t-value is set to 1.6...2.0 times the starting time of the motor. ...2.0 times.

The thermal overload pre-warning signal can warn the operator to reduce the load of the motor when thermal overload occurs, thus avoiding unnecessary thermal overload tripping.

This can avoid unnecessary thermal overload tripping. The setting value of the pre-warning signal can be individually set to a certain percentage of the thermal overload tripping value.

Therefore, by choosing the appropriate pre-warning signal setting value, the motor can be operated close to the thermal capacity limit value while avoiding tripping due to prolonged overload.

Every time the motor is started, the start-up monitoring unit monitors the thermal consumption of the motor, usually in accordance with the It formula.

Alternatively, a fixed time limit overcurrent can be used. The latter is mainly used for equipment with non-motor loads.

In either case, a speed switch signal such as that mounted on the motor shaft to distinguish between motor blocking and normal starting can be programmed into the relay to control the output trip command.

to control the output trip command. A high value overcurrent protection unit (current cut-off) for protection against short-circuits between motor windings and short-circuits between phases of feeder cables.

The current setting value can be set so that it is automatically doubled during start-up. Therefore, the setting value can be set lower than the motor starting current.

Normally it can be set as low as 0.75 times the motor starting current. In addition, an appropriate action time should be set to match.

In this way, when the motor is blocked during operation, the current interruption protection unit can ensure reliable operation.

When the motor is controlled by a contactor, the high value overcurrent protection unit should be blocked and the fuse should be used to protect against short circuits.

The non-directional earth fault unit detects earth faults in the motor and feeder circuits. In the neutral point directly grounded or through the low impedance grounding system, the CT can be connected to a residual ground fault.