Unit of УКРВ type is an independent product, which can be connected to a power supply cable crosscut of high-voltage distribution substation or transformer substation group, as well as to switchgear unit of high voltage distribution substation or central underground substation.
Unit of УКРВ type explosion-proof enclosure is a welded steel construction mounted on a sled. The enclosure is divided into two explosion-proof sec-tions: network section and capacitor unit section.
Network section is designed to connect the unit to the network and consists of the inlet box divided into two parts. It has two power cable glands to connect cables with an external diameter up to 67 mm, four cable glands to connect control cables with the external diameter up to 32 mm and two removable covers.
Information of the load current users is received from the built-in current transformer of 400/5 A (while connecting to the cable line), from the current transformer of the outcoming connection switchgear unit or from the current transformer of the 6 kV / 10 kV power supply switchgear unit.
Capacitor unit section consists of interconnected control and capacitor sections closed with covers.
Control section includes control and protection equipment, the interlock which disables the high-voltage section of the supplying switchgear unit while ope ning the front cover, 6 kV/ 10 kV carriagetype power contactor providing two visual circuit breaks, 6 kV/ 10 kV auxiliary voltage transformer to supply the contactor and control scheme.
Capacitors section includes 3-phase cosine power capacitors of the required power (1 or 2 pieces), 6 kV / 10kV, 100/5 A current transformers, capacitor shells explosion prevention device (in case of excessive swelling) based on a microswitch, capacitors protection temperature sensor, additional external cosine power capacitors discharge unit.
6 kV power circuits connection is made with the single-core high-voltage flexible cable.
Unit control elements (five buttons and two inspection windows) are placed onto the control section cover external surface. The unit enclosure is equipped with the external and the internal earthing clips.
Removable and openable enclosure covers are provided with a warning label: “Open in 5 minutes after power supply disconnection”.
Unit has the following lockouts:
- preventing unit repeated switch on immediately after its switch off. The repeated unit switch on is possible through the programmable time delay;
- switching off 6 kV/ 10 kV power supply switchgear unit while opening the network section cover, control section cover and capacitors section cover of the capacitor unit;
- switching off unit high-voltage contactor while attempt of rolling out the contactor switched on.
- unit is an independent product, which can be connected to a power supply cable crosscut of high-voltage distribution substation or transformer substation group, as well as to power supplying or outcoming switchgear unit of high-voltage distribution substation or central underground substation. Unit can be used with any type of switchgear unit.
- information of the load current users is received from the built-in current transformer (while connecting to the cable line), from the outcoming con-nection switchgear unit current transformer or from the power supply switchgear unit current transformer of highvoltage distribution substation or central underground substation where УКРВ unit is connected to.
Electric circuit of the units provides the following kinds of protections, lockouts, alarms and monitoring:
- operational local unit switching on and off;
- capacitors overload protection while increasing the current through the capacitors above the 130 % of the rated one;
- explosion prevention protection of the power cosine capacitor banks while their sides swelling;
- switching off the high-voltage section of switchgear unit supplying the УКРВ unit while opening the network section cover or capacitor section cover;
- switching off the unit high-voltage contactor while attempt of rolling out the contactor switched on;
- unit current measurement in the (three phases);
- separate alarms on:
- control and protection circuits supply AC voltage presence;
- 6 kV/ 10 kV contactor switched on (capacitors connected);
- 6 kV/ 10 kV contactor switched off (capacitors disconnected);
- overload protection actuation;
- capacitor explosion protection actuation.
Short-circuit currents protection of capacitor unit is performed by power supplying switchgear unit.
The capacitor unit corresponds to class I electrical shock protection according to the Standard of ГОСТ 12.2.007.0-75.
The electrical circuit diagram of the capacitor unit and Connection diagrams of the unit are given in data sheet.
Overall dimensions of the capacitor unit are given in drawing 1.