Typically, output power from the power system is divided to facilitate physical connections to the load. For example, a 21 Ampere redundant power system (two or more 21 Ampere power supplies) may be connected to ten loads drawing 1 Ampere, and 1 load drawing 10 Amperes. The distribution system provides the mechanical and electrical components necessary to connect the wires from the load to the DC bus. A DC distribution system for this example could be accomplished with a 22 position barrier strip: two positions (+ an -) for each of 11 loads.
Among the building blocks Kepco typically uses to accomplish this are
In addition, where dictated by the user application, protective devices and low voltage disconnects may also be included as part of the DC power distribution system.
Protective Devices
Protective devices may be used either on the entire DC bus, or on individual branches that go to each load. In the example above, there may be ten 1 Ampere and one 10 Ampere fuse circuits. Examples of the Protective device building blocks used in Kepco power distribution systems are circuit breakers as well as various types of fuses, including American style, indicating style, and Telco indicating style.
Low Voltage Disconnects
A low voltage disconnect is used when there is a battery floated across the DC bus. If AC fails, the battery powers the load and as the battery discharges, the voltage decays. If the voltage drops below a certain point, the battery will be destroyed, so to prevent this, the low voltage disconnect (generally, a normally open relay or contactor) is wired between the battery and the load. When the voltage drops to a predetermined level, the relay opens. When AC is restored, the power supply turns on, the disconnect closes and the load is run from the power supply while the battery is recharged.
- 30 Ampere Low voltage Disconnect
- 200 Ampere Low voltage Disconnect
