Installation guide

Site Requirements

890USE17100 September 2003 15

Sensor and

Actuator Power

The power distribution module (PDM) distributes field power across the island’s

sensor bus to all the input modules in a particular voltage group and along the

island’s actuator bus to all the output modules in that voltage group. Each PDM on

an island is supplied whatever voltage it will distribute to a particular voltage group

of I/Os (24 VDC, 115 VAC, or 230 VAC).

There are two types of PDMs used on an island (both use the STB XBA 2200 base):

An STB PDT 3100 module, which distributes field power to 24 VDC digital and/or

analog I/O modules

An STB PDT 2100 module, which distributes field power to either 115 VAC or

230 VAC digital I/O modules

You must choose an appropriate 24 VDC source power supply for the

STB PDT 3100. The STB PDT 2100 uses AC voltage.

Note: When an island bus is supporting both 115 VAC I/O modules and 230 VAC

I/O modules, the 115 VAC modules and the 230 VAC modules must be in separate

voltage groups behind separate STB PDT 2100 PDMs.

Note: PDM damage is possible if the actuator and sensor power sources, on a

115 VAC PDM, are from multiple phases of a source transformer/s. The

transformer will generate more than 300 VAC, which exceeds the PDM tolerance.

Multiple phases of a source transformer can generate more than 300 VAC. This

exceeds a 115 VAC PDM’s tolerance, and may cause damage.

The example below shows a 115 VAC PDM correctly wired to a two phase AC

power supply.

Phase 1

Phase 2

Two-phase Transformer

PDM

Actuator bus

Sensor bus

Opposite phase is not connected