powersoft Digam K4 - Chapter 3: Protection Mechanisms; 3.1 Turn-On;Turn-Off Muting; 3.2 Short Circuit Protection; 3.3 Thermal Protection System

15
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.
22