Cooper TP Workshop Manual_Scant:Layout 1 7/8 ... - Cooper Security

Electrical Noise 8136IDIS Sensor IDIS Sensor IDIS SensorIDIS SensorIDISSigExpander Card0V+12VIDIS Sensor IDIS Sensor IDIS SensorSig0V+12V0V+12VRemotePower SupplyFigure 14. Siting IDIS remote PSUIf the sensors are more or less evenly spaced along the wire an ideal split isto allow the panel to run a third of the sensors (those nearest it). The RemotePSU runs the remainder and is connected to the bus wires at a point in themiddle of the sensors it is supplying.If (as is probably the case) the sensors are grouped together in bunchesconnected to junction boxes then find the worst volt drop point in the systemby measurement. Trace the cables back towards the panel and find a pointthat has a volt drop about half as bad as the worst measurement. Connectthe PSU near this point.Note that if you fit the PSU at the far end of the cable and power all thesensors then you still may have an excessive 0V voltage drop between thepanel and the furthest sensor, but the voltage is now the other way round asthe current is flowing in the opposite direction along the 0V wire.ALWAYS isolate the PSU +ve from the panel +ve feed otherwise you willhave problems if either the PSU or panel stop working. Always ensure that ifthe remote PSU goes faulty it will cause some sort of warning.38 of 44 496339 Issue 4