Availability index for transmission facilities - DYSU - is calculated as the arithmetic mean of the values of the availability indices of 5 groups of transmission equipment including groups of lines and transformers installed at our substations. 

The availability of each group of these facilities is calculated as the ratio of the actual operating hours of the transmission facilities (in hours) per year to the nominal number of hours per year. 

The DYSU index is intended to monitor the readiness of transmission network elements to provide electricity transmission service and takes into account the availability of the 5 groups of transmission facilities listed below: 

1. Category L1 lines – international, radial and 400 kV lines with a peak load of over 300 MW, and 220 kV lines with a peak load of over 170 MW. 
2. Category L2 lines ─ other lines not mentioned in points 1 and 3. 
3. LB power unit lines – power output lines from power plants (connecting power plants with large near-plant substations). 
4. Transformers in category S11 substations – transformers in substations with interconnections to the systems of other countries, in near-plant substations and in substations coupling 400 kV and 220 kV grids. 
5. Transformers in category S22 substations – transformers in other substations not mentioned in point 4. 

Conducting monitoring of the operation and technical condition of the transmission grid 

Maintaining network assets requires the performance of ongoing monitoring of the operation and technical condition of various components in the transmission grid. The following operations monitoring services were set up for this task within the structures of the Operations Department: Monitoring Centre (CN) in Konstancin-Jeziorna and five Regional Monitoring Centres (RCN) at the head offices of branch divisions in Warsaw, Radom, Katowice, Poznań and Bydgoszcz. The monitoring services model has a hierarchical structure. The Regional Monitoring Centres functionally report to the Monitoring Centre and are responsible for a designated area of PSE's network assets.

Fig. Organisation of PSE S.A.'s operations monitoring services.

Warehouse management as an environmentally friendly initiative in line with the concept of a circular economy

Warehouse management at PSE primarily prevents the generation of a large amount of waste. This is achieved through, among other things:

• Warehousing of dismantled operable equipment; where dismantling involves operable equipment, the equipment is transferred for warehousing in a warehouse reserve, to be reused for troubleshooting or ongoing repairs. 
• Refurbishment of inoperable equipment. Once a failure or a fault has occurred, inoperable equipment is dismantled and, where possible, examined and sent for refurbishment. After refurbishment, the equipment is transferred to the warehouse reserve as operational and reusable.

In cases where equipment or materials have become obsolete and the company has decided not to carry out the refurbishment, tenders are organised for appropriate waste management. Insulating medium in equipment is often a hazardous waste according to the Waste Act. For this reason, PSE as the generator is responsible for the waste until its final disposal.

Waste management is carried out by transferring waste to companies which, within the scope of their activities, hold environmental decisions for final disposal. Our company requires proof from waste collectors not holding appropriate decisions on final disposal of hazardous waste that the treatment process has been carried out and that hazardous waste has been handed over for final disposal.Some equipment includes recyclable materials. These include, for example, oil, steel, copper and porcelain. These materials are subject to processing, recovery and reuse.

Our activities are in line with the concept of a circular economy, which makes the warehouse management process an indirectly environmentally friendly activity.