Emergency Loads

Typical units and machineries to be considered as emergency loads  

More equipments can be added to this list as per need in the plant. 

The sequence of starting various equipments is to be decided by plant engineers (generally safety systems, control instruments, and boiler feed water are started first and are followed by effluent control and scrubbing systems. Production units are started in the end). 

Power required for other equipments which are run intermittently—such as hoists, cranes, belt and bucket conveyors, filters, and water pumps for filling up overhead 

These are loads due to welding sets, drilling machines, fabrication machineries, travelling cranes, hoists installed in the (centralised) workshop. These facilities are very useful for in-house repairs of plant equipments and for some fabrication. 

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Emergency loads Loads that are only applied on loss of normal supplies. These are usually supplied only for a fixed period of time (e.g. turbine emergency mndown lube oil pump). 

These loads, the expected duration of emergency loads and the required switching regime and number of operations must be specified at the time of order placement. 

Diesel-powered generators will be used. The emergency generator will be sized to handle 100% of the connected emergency load. 

The role of the power supply to guarantee the ESFAS actuation is fundamental. To respect the original design, each division has an Emergency Load Shedding System (ELS) to start a diesel generator. 

Common requirements for the reactor protection system, engineered safety features actuation system and emergency load sequencer on one side, and for the reactor limitation system on the other side have been set forth in the following areas ... 

These are generally provided to supply power for emergency loads rather than for running the entire plant. 

Maximum starting load the DG set can take— to match with emergency loads planned by purchaser. 

It also has to be recognized that the measurements obtained did not include a mud rush or any other specific emergency loading condition. Design for normal working pressures is not a safe design procedure when it is known that extreme or emergency conditions do occur. 

Each part of SANS 10208 specifies emergency loads, which cover the hazards relevant to the different structures. Specification of these loads has arisen from consideration of the risks associated with mining structures. The risks have been assessed and described by Anglo American (2011) and SIMRAC (2004) and many others. The major risks to mine shafts and hoisting listed by Anglo American (2011) are ... 

The load factors applicable to emergency loads differ from those applicable to operating loads, because the emergency loads define extreme loads which cannot be exceeded. For example in most cases the major emergency load is the hoist rope break load. This load is well known, so the load factor applied is 1,05. 

In general, automatic transfer switches are provided for code-required emergency loads, and manual transfer switches are provided to change from a main to a standby fen or pump, or to change from a normal to redundant power source. (See Fig. 4.)... 

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