The UZK 12 service panel
The UZK 12 service panel is intended for operation in 50 Hz AC power distribution systems rated up to 12 kV
Application and features of the system
The UZK 12 service panel facilitates connection of power supply cables (like YKY, YHKXS, and OG) to direct feeders of power loads (e.g. made with PROTOLON or OG flexible cords).
The UZK 12 service panel can be provided with surge arrestors and serve as an overvoltage protection component.
The UZK 12 service panel is intended for operation in 50 Hz AC power distribution systems rated up to 12 kV.
The UZK 12 service panel can be provided with interlocks to control the servicing of the devices inside of the panel in dependence from the status of external equipment units (like the switchboards which feed the service panel’s incomer) or to control the switching of external equipment units in dependence from the status of the interlocked UZK 12 service panel.
The protection level and design can enable indoor or outdoor operation of the UZK 12 service panels.
The UZK 12 service panel can be provided with interlocks to control the opening of the panel in dependence from the status of external equipment (e.g. the earth switch in the switchboard which feeds the service panel’s incomer). The interlocks can be mechanical (key-operated) or electromechanical.
The UZK 12 service panel is a welded and bolted structure with suitable ingress protection, and the corrosion protection is provided with paint coats selected according to the environmental conditions specified for the operating site.
The structure is made of 2 mm sheet steel with additional reinforcement to provide safety against internal arc discharge within the rated current limits. The service panel’s roof features a safety relief designed to open in the event of an explosive and sufficiently high internal pressure rise from an internal arc discharge to eliminate the risk of the UZK 12 enclosure integrity failure. The safety relief is designed as a bent and welded cover fastened to the panel’s enclosure with sufficiently strong hinges and provided with closure seals to ensure the required protection rating.
Single or three-core cables are fed into the service panel from the bottom or, optionally, from the side (either left or right-hand) through dedicated cable conduits which ensure a correct seal. The UZK 12 service panel is designed to accommodate cables in plastic insulation. Paper-insulated cables can be accommodated by small-size service panels only and requires prior consultation with the service panel manufacturer.
The UZK 12 service panel is available in two basic sizes which vary in overall dimensions. Each version is designed for the current parameters specified in the ratings.
Figure 1. Example view of UZK 12 service panel
Figure 2. Typical main diagrams of UZK12 service panel
Technical data and certificates
| Type - Version | UZK 12-4 | UZK 12-6 |
|---|---|---|
| Rated insulation voltage Ur | 12kV | |
| Rated frequency fr / number of phases | 50Hz/3 | |
| Power frequency short-time withstand voltage - Ud – line-to-line and to earth/enclosure | 28kV | |
| Withstand lightning impulse voltage (1.2/50 µs) – Up - line-to-line and to earth/enclosure | 75kV | |
| Rated continuous current Ir | 400A | 630A |
| Rated short time withstand current Ik/tk | 31,5kA/1s | |
| Rated peak withstand current Ip | 80kA | |
| Withstand for internal arcing fault IA | 31,5kA/0,1s | |
| IAC classification (class of resistance to internal arc) | AFLR | |
| Degree of protection | IP55 | |
| Dimensions (WxDxH) mm | 800/2055/350 | 800/2055/450 |
*) - without external guards, covers, doors
Compliance with standards PN-EN 62271-200:2012, PN-EN 62271-1: 2018-02.
Certificates
The UZK 12 service panels were tested at the Institute of Electrotechnics in Warsaw and come with the Certificates verifying their rated parameters and admitting them for use at power distribution plants, power stations, industrial plants and other facilities generating, transmitting or using electric energy.