Connecting DC power to the IM7200

The IM7200 Infrastructure Manager can be ordered to suit AC or DC powered environments. The universal Dual AC (100~240V) models use IEC sockets and power cords with regional AC plugs (IM72XX-2-DAC). The Dual DC models (IM72XX-2-DDC) are supplied with dual removable screw terminal blocks which are normally wired into conductors from the DC plant. 

The Dual DC model includes two internal “nominal 48V” DC-DC converters (a & b). Each DC power input has screw terminals that take the positive (+), negative (–) and ground conductors from the DC plant voltage feed directly as long as the voltage across them is in the range 36V~72V DC. As the IM72XX-2-DDC supports two DC inputs, separate DC feeds are wired to each input for high availability. Only one DC input supplies power ot the IM7200 at any time however, if one feed fails, the other automatically supplies power. The screw terminals are at the rear face of the IM7200 and labelled +Va, -Va,  +Vb, -Vb and Ea, Eb. Power to the IM7200 from each terminal block is controlled by an on/off DC power switch.

 

Connecting a chassis ground conductor often depends on the DC plant or telco safety requirements but normally it is wired from the IM7200 chassis earth terminals (Ea and Eb ) to the required earthing point of the desired chassis or frame.

To initially connect DC power, ensure each DC power switch is in the off or “0” position. Then unplug the 3 pin removable terminal block and screw in the stripped ground conductor wire first (Ea or Eb), then screw in the stripped positive (+) conductor to +Va or +Vb and finally screw in the stripped negative (-) conductor to –Va or –Vb respectively. Now the DC power switch can be pushed into the on or “1” position for normal operation.

Sometimes the + and – nature of DC plant power can be confusing depending on the DC power source, the -48V (negative terminal) might be marked with a minus (-) symbol, and the -48V return (positive terminal) might be marked with a positive (+) symbol.

When removing DC power from the unit for maintenance or redeployment, firstly ensure the DC power switch is off or in the “0” position then unscrew +Va or +Vb, conductor after that unscrew the -Va or –Vb conductor and finally the earth conductor Ea or Eb.

If you are removing the DC screw terminal plug temporarily and don’t want to remove the DC feed conductors, ensure the terminal block is removed and installed only with the DC power switch in the off or “0” position, this will eliminate any possibility of arcing.