At which side of Relay you see the 3 pins or 3 terminal– This side the middle pin of both side pin is the Common (COM) for the Load input (AC or DC). And both side pins are the DC Input supply pin for the coil of relay.
So the which you see the 3 terminal – here you both side (Except middle) pins are connect with DC supply for relay input.
And which side you see the only 2 terminals – These 2 terminals are for Load Output . In which one is NC (normarrly Connected) and one is NO (Normally opened) . For finding which pin is NO and Which Is NC use the multimeter or ant continuty tester.
OR
Generally On PCB Relays -there are pin connection name is denoted on relay body near the all pins.
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