• What is the minimum Bussed Power value to power a field transmitter ?

• Can I have redundant power supplies ?

• Do I need a power supply for 24V DC ?

• How does power supply redundancy for 2/1 systems work?

• What output power surge is available from the MTL8913 / 8914

What is the minimum Bussed Power value to power a field transmitter ?

Can I have redundant power supplies ?

Yes. The supply modules powering the system and the bussed field power may be duplicated for redundancy, thus maintaining system operation during failure of any given supply.

When using DC power sources, two identical DC supply modules (8910-PS-DC) can be fitted on the 8711-CA-NS or 8712-CA-NS ‘Node Services’ Carrier. Alternatively, if the BIM is mounted on an 8718-CA-NS Node Services carrier, 8910 modules may be mounted on 8717-CA-PS carriers adjacent to the 8718.

For AC mains-powered nodes two 8913-PS-AC power supplies can be connected in redundant mode to the 8715-CA-BI Universal Carrier or 8718-CA-NS Node Services carrier. The latter carrier also has inputs for power fail signals from the 8913-PS-AC / 8914-PS-AC, and when fitted with the 8510-MO-NS, detects any power supply failure. This failure may then be transmitted to the host system such that corrective action be taken.

Redundant supplies for Bussed Field Power can also be provided by the 8914-PS-AC.

For further details on supplying redundant power see Instruction Manual INM8900

Do I need a power supply for 24V DC ?

When an MTL system is required to supply 24V DC to a field instrument, then a 24Vdc supply is required. This ‘Field Power’ is distributed to the individual modules via their carrier and is termed ‘Bussed Field Power’.

Note that this applies only to Non-IS applications; the IS portion of any node utilises dedicated power units (8920-PS-DC).

How does power supply redundancy work for 2/1 systems?

I/O module power supplies (type 8920-PS-DC) for the 2/1 system provide 12V DC power for (2/1) IS - I/O modules and their field wiring.

One power supply will typically power eight 2/1 I/O modules.

If the system requires more than one 12V power supply, additional 8920 PSUs are inserted in the line of carriers, thus providing additional current capacity onto the Railbus supplying the I/O modules.

For redundancy, one extra 8920 PSU can be inserted in the system. This will provide the necessary power to continue full operation if one of the other 8920 supplies should fail. The failure of the power supply is signalled to the BIM so that replacement can be carried out as soon as possible.

What output power surge is available from the MTL8913 / 8914

The MTL8913 & MTL8914 power supplies can deliver 150% of the output rating for a maximum of 1 second.

Both units function with 85– 264 V AC input voltage and may be mounted in Zone 2 / Div 2.