Nidec DFS Series Power Installation Manual

DFS1/DFS2 Power Installation Guide 45Issue Number: 2Safety information Product information Mechanical installation Electrical installation Technical dataSpecial precautions are recommended if drive is operated with a motor cable length > 10 m undereither of the following conditions:690 Vac supply voltage400 Vac operation with continuous or very frequent sustained braking and motor cable length> 10 m.Under these conditions, it is recommended that an inverter-rated motor be used. Inverter-ratedmotors use a reinforced insulation system intended by the manufacturer for repetitive fast-risingpulsed voltage operation.If it is not practical to use an inverter-rated motor, an output choke (inductor) should be used.The recommended type is a simple iron-cored component with a reactance of about 2 %. The exactvalue is not critical. This operates in conjunction with the capacitance of the motor cable to increasethe rise-time of the motor terminal voltage and prevent excessive electrical stress.4.20 Star/ Delta motor operationThe voltage rating for Star and Delta connections to the motor should always be checked beforeattempting to run the motor.The default setting of the motor rated voltage parameter is the same as the drive rated voltage,i.e. 400 V drive 400 V rated voltage.A typical 3 phase motor would be connected in Star for 400 V operation and in Delta for 230 Voperation. However, variations on this principle are common e.g. 690 V Star and 400 V Delta.Incorrect connection of the windings will cause severe under or over fluxing of the motor.Under-fluxing results in very poor output torque. Over-fluxing leads to motor saturation andoverheating.4.21 External 24 V DC Supplies4.21.1 Control supplyAn external 24 Vdc supply can be connected to control terminals to provide the following functions:• To supplement the internal 24 V supply when multiple option modules are being used and thecurrent drawn by the modules is greater than the drive can supply.• As a back-up power supply to keep the control circuits powered up when the AC power supply isremoved. This allows any fieldbus modules, application modules, encoders or serialcommunications to continue to operate.• To set up the drive using the keypad when the AC power supply is not available. However, thedrive will be in the Under-voltage state unless either line power supply or low voltage DCoperation is enabled, therefore diagnostics may not be possible. (Power down save parametersare not saved when using the 24 V back-up power supply input).For further information see the Unidrive M700, M701, M702 Control User Guide. CT Part Number:0478-0353-02.4.21.2 Backup supplyThe power 24 Vdc supply (terminals 51, 52) can be connected to allow the 24 Vdc supply to be usedas a backup supply.If the 24 Vdc backup supply is not connected the message "Waiting For Power System" will bedisplayed on the keypad and no drive operations are possible.For further information see the Unidrive M700, M701, M702 Control User Guide. CT Part Number:0478-0353-02.