powersoft Digam K20 - Chapter 3: Protection Features; Muting and Short Circuit Protection; Thermal Protection; DC Fault & Input;Output Protection

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3Protection
3.1Turn-On/Turn-Offmuting
Foraboutfoursecondsafterturn-on,andimmediatelyatturn-off,theamplifieroutputsaremuted.
3.2Shortcircuitprotection
A shortcircuitprotectionsystemsafeguardstheamplifier'soutputtransistorsundershortcircuitsandotherstressfulloads.
Itiscompletelyinaudiblewheninactive.Incaseofshortcircuit,theredLEDwillbelight-upandwriting"PROT"appearsin
thefirstlineofthedisplay(seePar.2.2foradetaileddescription). Theamplifierwillresethimself50timesevery2seconds.
Once50resetshavebeenperformedandthefaultstillexistontheoutput,theunitsetsintosteadyprotectionmode. Turn
ON/OFFcycleisneededtorestarttheunit.
3.3Thermalprotection
A DIGAMamplifierusesacontinuouslyvariablespeedfantoassistcooling(thefanspeedchangesinresponsetothe
amplifier'scoolingneeds).Iftheheatsinktemperaturereachesapproximately80°C,theyellowLEDstartstoflashing.Ifthe
temperatureismorethen85°Cthethermalsensingcircuitrywillmuteeachpowersectionchannels,theLEDwilllight
permanentlyandthepowersupplywillbecutoff.Oncetheheatsinkhascooleddown,theamplifierwillautomaticallyreset
andtheLEDwillbegoout.Itispossibletoreducethetemperaturebyreducingtheoutputpower.
3.4DCfaultprotection
IfDCorexcessivesubsonicenergyappearsatachanneloutput,aninstantaneousprotectioncircuitwillcutoffthepower
supplyforbothchannels.Powersupplyshutdownisusedinsteadofspeakerrelays,therebyimprovingthedampingfactor
andreliabilityoftheDIGAMamplifiers.
3.5Input/Outputprotection
AnultrasonicnetworkdecouplesRFfromtheoutputsandkeepstheamplifierstablewithreactiveloads.
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