Danfoss VLT AutomationDrive FC 302 Design Manual

Also see for VLT AutomationDrive FC 302: Service guide Programming guide Instruction manual Installation guide Operating guide

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Danfoss VLT AutomationDrive FC 302 Design Manual Manual pdf 160 page image

NOTICEMonitoring the brake power is not a safety function; athermal switch connected to an external contactor isrequired for that purpose. The brake resistor circuit isnot ground leakage protected.Overvoltage control (OVC) can be selected as an alternativebrake function in parameter 2-17 Over-voltage Control. Thisfunction is active for all units and ensures that if the DC-link voltage increases, the output frequency also increasesto limit the voltage from the DC link, which avoids a trip.NOTICEOVC cannot be activated when running a PM motor,while parameter 1-10 Motor Construction is set to [1] PMnon-salient SPM.10.8 Residual Current Devices (RCD) andInsulation Resistance Monitor (IRM)Use RCD relays, multiple protective grounding, orgrounding as extra protection, provided they comply withlocal safety regulations.If a ground fault appears, a DC current can develop in thefaulty current. If RCD relays are used, local regulationsmust be observed. Relays must be suitable for protectionof 3-phase equipment with a bridge rectifier and for a briefdischarge on power-up. See chapter 10.9 Leakage Currentfor more details.10.9 Leakage CurrentFollow national and local codes regarding protectivegrounding of equipment where leakage current exceeds3.5 mA.Drive technology implies high-frequency switching at highpower. This high-frequency switching generates a leakagecurrent in the ground connection.The ground leakage current is made up of several contri-butions and depends on various system configurations,including:• RFI filtering.• Motor cable length.• Motor cable shielding.• Drive power.130BB955.12abLeakage currentMotor cable lengthIllustration 10.12 Motor cable length and power size influencethe leakage current. Power size a > power size b.The leakage current also depends on the line distortion.130BB956.12THDv=0%THDv=5%Leakage currentIllustration 10.13 Line Distortion Influences Leakage CurrentIf the leakage current exceeds 3.5 mA, compliance withEN/IEC61800-5-1 (power drive system product standard)requires special care.Reinforce grounding with the following protective groundconnection requirements:• Ground wire (terminal 95) of at least 10 mm2(8 AWG) cross-section.• 2 separate ground wires both complying with thedimensioning rules.See EN/IEC61800-5-1 and EN 50178 for further information.Electrical Installation Con... VLT® AutomationDrive FC 302158 Danfoss A/S © 01/2018 All rights reserved. MG38C2021010