Nidec Digitax HD M75 Series Installation And Technical Manual

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Nidec Digitax HD M75 Series Installation And Technical Manual Manual pdf 82 page image

Safety information Product information Mechanical installation Electrical installation Multi axis system design Technical data82 Digitax HD M75X Series Installation and Technical GuideIssue Number: 54.13.2 Digitax HD M751 EIA 485 serialcommunicationsThe EIA-485 interface provides two parallel RJ45 connectors allowingeasy daisy chaining, refer to Figure 4-29 Location of the communicationconnectors on page 81. The drive supports Modbus RTU protocol. SeeTable 4-23 for the connection details.Standard Ethernet cables are not recommended for use whenconnecting drives on a EIA-485 network as they do not have the correcttwisted pairs for the pinout of the serial comms port.Table 4-23 Serial communication port pin-outsMinimum number of connections are 2, 3, 7 and shield.4.13.3 Digitax HD M751 Isolation of the EIA-485serial communications portThe serial communications port is double insulated from the high voltagedrive circuits and meets the requirements for PELV (Protective ExtraLow Voltage) according to IEC61800-5-1. The communications portsremain referenced to other PELV rated circuits within the drive (includingthe control, feedback and digital I/O). Where further isolation from thesePELV rated circuits is required and additional external isolation barrierwill be required.An isolated serial communications lead has been designed to connectthe drive to IT equipment (such as laptop computers), and is availablefrom the supplier of the drive. See below for details:Table 4-24 Isolated serial comms lead detailsThe “isolated serial communications” lead has reinforced insulation asdefined in IEC60950 for altitudes up to 3,000 m.4.13.4 Communication networks and cablingAny isolated signal circuit has the capability to become live throughaccidental contact with other conductors; as such they should always bedouble-insulated from live parts. The routing of network and signal wiresshould be done so as to avoid close proximity to mains voltage cabling.4.14 Safe Torque Off (STO)The Safe Torque Off function provides a means for preventing the drivefrom generating torque in the motor, with a very high level of integrity. Itis suitable for incorporation into a safety system for a machine. It is alsosuitable for use as a conventional drive enable input.The safety function is active when the STO input is in the logic-low stateas specified in the control terminal specification. The function is definedaccording to EN 61800-5-2 and IEC 61800-5-2 as follows. (In thesestandards a drive offering safety-related functions is referred to as aPDS(SR)):'Power that can cause rotation (or motion in the case of a linear motor) isnot applied to the motor. The PDS(SR) will not provide energy to themotor which can generate torque (or force in the case of a linear motor)'This safety function corresponds to an uncontrolled stop in accordancewith stop category 0 of IEC 60204-1.The Safe Torque Off function makes use of the special property of aninverter drive with an induction motor, which is that torque cannot begenerated without the continuous correct active behaviour of the invertercircuit. All credible faults in the inverter power circuit cause a loss oftorque generation.Note on the use of servo motors, other permanent-magnet motors,reluctance motors and salient-pole induction motors:When the drive is disabled through Safe Torque Off, a possible(although highly unlikely) failure mode is for two power devices in theinverter circuit to conduct incorrectly.This fault cannot produce a steady rotating torque in any AC motor. Itproduces no torque in a conventional induction motor with a cage rotor.If the rotor has permanent magnets and/or saliency, then a transientalignment torque may occur. The motor may briefly try to rotate by up to180° electrical, for a permanent magnet motor, or 90° electrical, for asalient pole induction motor or reluctance motor. This possible failuremode must be allowed for in the machine design.The Safe Torque Off function is fail-safe, so when the Safe Torque Offinput is disconnected the drive will not operate the motor, even if acombination of components within the drive has failed. Most componentfailures are revealed by the drive failing to operate. Safe Torque Off isalso independent of the drive firmware. This meets the requirements ofthe following standards, for the prevention of operation of the motor.Machinery ApplicationsThe Safe Torque Off function is suitable for use as a safety componentof a machine:Safety ParametersAccording to IEC 61508-1 to 7 / EN 61800-5-2 / EN 62061If an Ethernet network adaptor is inadvertently connected toa Digitax HD M751 EIA-485 drive, a low impedance loadacross the EIA-485 24 V is applied and if connected for asignificant period of time can introduce the potential risk ofdamage.Pin Function1 120  Termination resistor2 RX TX3 Isolated 0 V4 +24 V (100 mA)5 Isolated 0 V6 TX enable7 RX\ TX\8 RX\ TX\ (if termination resistors are required, link to pin 1)Shell Isolated 0 VIn order to meet the requirements for SELV in IEC60950 (ITequipment) it is necessary for the control computer to begrounded. Alternatively, when a lap-top or similar device isused which has no provision for grounding, an isolationdevice must be incorporated in the communications lead.Part number Description4500-0096 USB Comms cableNOTECAUTIONWARNINGType Value Percentage of SIL3 allowanceProof test interval 20 yearsHigh demand or a continuous mode of operationPFH (1/h) 4.21 x 10-11 1/h <1 %Low demand mode of operation (not EN 61800-5-2)PFDavg 3.68 x 10-6 < 1 %