wire colors

Electrical Wire Markings
Electrical wires have markings stamped or printed on the outside sheath of the cable. These markings tell what type and size of wire that you have. But looking deeper, the color of the wires inside of the sheath, like in type NM cable, will reveal that different color wires serve different purposes.

Black Wires
Black wires are always used for hot wires. These wires may feed a switch or outlet and are often used as switch legs. Never used a black wire for a neutral or ground connection.
 
Red Wires
Red wires are also used for hot wires, switch legs (like to a ceiling fan), and are the second hot wire in 220-volt installations. Another useful application is the interconnect wire between two hardwired smoke detectors.
Blue and Yellow Wires
Blue and yellow wires are used as hot wires. These wires are usually pulled in conduit. The blue wires are generally used for travelers in three-way and four-way switch applications. They also are used as switch legs to things like lights and fans. Yellow wires are generally used for switch legs. These control things like light, fans, and switched outlets.
Green and Bare Copper Wires
Green wires and bare copper wires are used only for grounding. These wires will ground devices and shall be bonded to junction boxes and appliance connections for safety.
Wire Color Exceptions
In certain instances, wire colors may be used for connections that don't follow these general rules. For instance, a white wire in a two-conductor cable may be used for the second hot wire on a 240-volt appliance or outlet connection. Another application is using the white wire for a switch leg for lighting or running a three-way switch application. This white wire should be properly marked to show that it is being used for something other than a neutral. Simply mark the end of the wire with black or red electrical tape. That way, no one will be confused and accidentally use it for something else.



 

Demand Side Management

Demand Side Management

DSM encompasses “systematic utility and government activities designed to change the amount and/or timing of the customer’s use of electricity” for the collective benefit of the society, the utility and its customers. As such, it is an umbrella term that includes several different load shape objectives, including load management (LM), energy efficiency (EE) and electrification.

DSM Objectives

DSM objectives are normally categorised into Corporate, Load Shape and Non-Load Shape objectives and are described below.

Corporate Objectives

In order for the CEB to achieve its Mission it has set operational and management objectives. This would include improving power quality and reliability, minimizing pilferage, reducing system losses, improving the distribution network, upgrading sub-stations, high collection efficiency, improving customer service etc.

Load Shape Objectives

Inevitably, as DSM is being considered primarily as a cost-effective alternative to supply-side options, the extent to which a given DSM program meets the CEB’s load shape objectives is of paramount consideration. Like supply-side options, DSM options generally primarily address one of the following specific load shape objectives

peak clipping	the reduction of utility load primarily during periods of peak demand
valley-filling	the improvement of system load factor by building load in off-peak periods
load shifting	the reduction of utility loads during periods of peak demand, while at the same time building load in
	off-peak periods. Load shifting typically does not substantially alter total electricity sales.
conservation	the reduction of utility loads, more or less equally, during all or most hours of the day
load building	the increase of utility loads, more or less equally, during all or most hours of the day
provision of a more
flexible utility load shape	refers to programs that set up utility options to alter customer energy consumption on an as-needed basis,as in interruptible / curtailable agreements

Details Owner By : CEB
we get from :- http://www.ceb.lk/sub/knowledge/demandside.html

Posted by ....>>  (electrical section 2011-2013) Technical college Hasalaka

Hydro Power Plant Operation

 Hydro Power Plant Operation

Laxapana Complex

Laxapana Complex can be described as Kehelgamu – Maskeli Oya complex, as the five power stations in the Laxapana Complex are situated along Kehelgamu oya and Maskeli Oya. The main large reservoir at the top of Kehelgamu oya is Castlereagh reservoir, where the rain water from the catchment area above the reservoir gets collected. Main reservoir associated with Maskeli oya is Maussakelle reservoir.
Water collected in the Castlereagh reservoir is brought down along a power tunnel toWimalasurendra power station to operate the two hydro turbine-generators, each 25 MW in capacity. Water released from Wimalasurendra power plants after operation, gets collected in Norton pond, which is not a large reservoir. This water is brought down along another tunnel to Old Laxapana power station to operate five turbine-generator units, where 03 units are of 8.33 MW and other two units of 12.5 MW. Water released after operations of Old Laxapana machines gets collected in Laxapana pond.
Similarly. Water collected in Maussakelle reservoir is taken along a tunnel to operate the two Canyon machines of 30 MW each. Water discharged after operations gets collected in Canyon pond. This water is brought down along another tunnel to operate the two New Laxapana machines which are 50 MW each.These two machines release the water to Laxapana pond as Old Laxapana machines.
Water collected in Laxapana pond is taken along a tunnel to operate the two machines, which are 37.5 MW each, at Samanala power station at Polpitiya. Water released from Samanala machines flow into the Kelani river,which forms by Kehelgamu oya and Maskeli oya.

 

Mahaweli Complex

The first reservoir in Mahaweli complex is the Kotmale reservoir. Water is taken to operate the three turbine –generator units (each of 67 MW) at Kotmale power station. Water released after operations flows along the river into the Polgolla barrage, which is a small pond. From Polgolla barrage, water is diverted to North Central province for irrigation and other purposes. This is done by carrying the water through a long tunnel to Ukuwela power station to operate two 20 MW machines. Water released after operating these 02 units flow to Bowatenna reservoir. Water is sent to Anuradhapura district direct from Bowatenna reservoir, and water used to operate the 40 MW machine at Bowatenna power station is sent to Elahera anicut, again to distribute for irrigation.

When water spills over the Polgolla barrage, during rainy seasons, it flows along the Mahaweli river to the large Victoria reservoir. The three 70 MW hydro units at Victoria power station operates using water from Victoria reservoir. Water released after operations at Victoria power station flows to Randenigala reservoir, which is the largest reservoir in Mahaweli complex. Water at Randenigala reservoir is used to operate the two 60 MW machines at Randenigala power station and then released to Rantambe reservoir. Though said a reservoir, it is also a small pond which can be regulated. Water at Rantambe pond is taken to operate the two machines at Rantambe power station, which are of 25 MW capacity each. The discharged water from Rantambe power station is sent to Minipe anicut. This water is then distributed to right and left banks of Minipe canals to use for downstream irrigation and other purposes.

The primary objective of the Mahaweli system is to provide water to irrigation and other usages. Power generation is the secondary purpose. Ceylon Electricity Board and Water Management Secretariat of Mahaweli Authority of Sri Lanka jointly decides the water utilisation of these reservoirs, in a manner which both parties benefit, ultimately giving the maximum benefit to the country........ Owner By : CEB we got from details :- http://www.ceb.lk/sub/knowledge/hydropower.html Posted by ....>>  (electrical section 2011-2013) Technical college Hasalaka