NKU RTZO-I LOW-VOLTAGE SWITCHGEARS

RTZO-I assembly

The NKU RTZO-I low-voltage switchgears – three-phase alternating current distributors of closed version, one-way service are designated to distribute electric power to low-power users.

Composition of NKU RTZO-I:

• an input cabinet (ShV);
• a functional control cabinet (ShFnU) with the following types of units: BUZ – stop valve control unit; BUD – motor control unit; BUK – valve control unit; BRs – distribution unit. Up to 12 BUZ, BUK, BUD units or up to 36 BRs units can be installed into ShFnU.

Up to seven ShFnUs with one ShV can be consolidated into RTZO assembly.

Functions of NKU RTZO-I:

• ShV is intended to perform following functions:

• - receiving three-phase alternating current on two inputs;
• - distributing AC electric power into the main circuits of ShFnU cabinets and protecting the main circuits against overload currents and short circuit;
• - automatic backup actuation assuring input power supply with the possibility to adjust the following parameters:

• U_min - if a value of input voltage of any phase is less than U_min, transition to the backup input is carried out;
• U_max - if a value of input voltage of any phase is more than U_max, transition to the backup input is carried out;
• automatic transition from the backup input to the main one;
• delay time for transition from the main input to the backup one; delay time for transition from the backup input to the main one;

• acquiring and transferring diagnostic information into an input-output module of ShFnU through electric communication lines;
• voltage availability monitoring and displaying operating voltage parameters of the main circuit, alarm generating in case of its deviation from a norm or a fault;

• ShFnU is intended to perform the following functions:

• distributing with BRs electric power of three-phase alternating current with voltage 400/230 V, with frequency 50 Hz, with current consumption monitoring;
• controlling actuators with BUZ, BUK, and BUD units having software adjusted for a certain type of actuators;
• broadcasting three-phase alternating current up to 100 A on each phase and with voltage 400/230 V to other ShFnUs of an RTZO assembly;
• outputting drive control commands;
• diagnosing actuator equipment operability and outputting diagnostic information via a digital interface;
• alarm generating by results of diagnostics.

RTZO-I assembly with open ShFnU

Key characteristics:

• significant reduction of equipment as compared to RTZO-69 and RTZO-88 due to increase of quantity of connections in one cabinet (up to 12 connections depending on version);
• reduction by up to 8 times of cable connections in comparison with current RTZO-69 and RTZO-88 due to a digital optical interface with the upper control level;
• quick change of cabinet configuration to assure interaction with different types of actuators defined by a customer;
• possibility of fast recovery of operability without switching off the power supply of a cabinet or an RTZO assembly;
• ease of operation and maintenance due to use of unified replaceable modules;
• a power cable can be inputted into an ShV cabinet both from the top and from the bottom of the cabinet;
• connection type of control units (BUZ, BUD, BUK) and BRs – pull-out;
• settings of control units are changed from the front panel;
• availability of a built-in valve diagnostics function allowing quick evaluation of current technical state of valves and its separate nodes;
• a checking algorithm is implemented in control units, the algorithm assures simulation of control command execution without its physical generation;
• control units can be in three states: operating, testing, and switched off. Check and adjustment are carried out in the testing state, herein power, input, and output circuits are switched off;
• load power range – from 0.1 tо 22 kW;
• operating voltages – ~230, ~ 400 V;
• operating voltages of control circuits – ~ 230, —24 V;
• rated current of an RTZO assembly – 100 А;
• insulation strength of power circuits – 2100 V DC;
• insulation strength of control circuits – 1500 V DC.

Diagnostic functions:

• monitoring power supply;
• monitoring currents of load on three phases;
• monitoring state of end switches;
• monitoring execution of control commands with determination of a command source;
• determining cos φ;
• monitoring symmetry of supply voltage and current consumption of actuators;
• monitoring phase interlacing;
• acquiring and transmitting diagnostic information.

Seismic resistance: cat. I according to PNEG-5-006 (7 points).

EMC: group IV according to SOU NAEK 100:2016.

Protection types of an electric motor:

• thermal protection;
• against short-circuit currents.

Ambient temperature range – from plus 5 to plus 60 °С.

Safety class – 2.

Safety category – А.

Degree of protection – IP31.

Life – 30 years.

Implementation facilities:

Zaporizhzhya NPP