Danfoss VLT AQUA Drive FC 202 Design Manual

Also see for VLT AQUA Drive FC 202: Service guide Installation guide Installation guide Operating guide Installation guide

Contents

2.12 Galvanic Isolation (PELV)2.12.1 PELV - Protective Extra Low VoltageWARNINGInstallation at high altitude:380-500 V, enclosure D, E, and F: At altitudes above 3km, contact Danfoss regarding PELV.525–690 V: At altitudes above 2 km, contact Danfossregarding PELV.WARNINGTouching the electrical parts could be fatal - even afterthe equipment has been disconnected from mains.Before touching any electrical parts, wait at least theamount of time indicated in Table 2.1.Shorter time is allowed only if indicated on the specificunit’s nameplate.Also make sure that other voltage inputs have beendisconnected.Protection against electric shock is ensured when theelectrical supply is of the PELV type and the installationcomplies with local/national regulations on PELV supplies.All control terminals and relay terminals 01-03/04-06comply with PELV. This does not apply to grounded Deltaleg above 400 V. Galvanic isolation is obtained by fulfillingrequirements for higher isolation and by providing therelevant creepage/clearance distances. These requirementsare described in the EN 61800-5-1 standard.To maintain PELV, all connections made to the controlterminals must be PELV. The components that make upthe electrical isolation also comply with the requirementsfor higher isolation and the relevant test as described inEN 61800-5-1.The PELV galvanic isolation can be shown in 6 locations, asshown in Illustration 2.20.1. Power supply (SMPS) including signal isolation ofUDC, indicating the intermediate current voltage.2. Gate drive that runs the IGBTs (triggertransformers/opto-couplers).3. Current transducers.4. Optocoupler, brake module.5. Internal inrush, RFI, and temperaturemeasurement circuits.6. Custom relays.130BA056.101325 46baMIllustration 2.20 Galvanic IsolationThe functional galvanic isolation - indicated by a and b inIllustration 2.20 - is for the 24 V backup option and for theRS-485 standard bus interface.2.13 Earth Leakage CurrentFollow national and local codes regarding protectiveearthing of equipment with a leakage current >3.5 mA.Frequency converter technology implies high frequencyswitching at high power, which generates a leakagecurrent in the earth connection. A fault current at thefrequency converter’s output power terminals couldcontain a DC component that can charge the filtercapacitors and cause a transient earth current.The earth leakage current is affected by the following:• RFI filtering• screened motor cables• frequency converter power (see Illustration 2.21)• line distortion (see Illustration 2.22)130BB955.12abLeakage currentMotor cable lengthIllustration 2.21 Influence of the Cable Length and Power Sizeon the Leakage CurrentIntroduction Design GuideMG20Z202 Danfoss A/S © Rev. 06/2014 All rights reserved. 352 2