When remote control channel is formed, the following channels can be utilized.

-channels for other purpose or power lines (underground cable line, overhead line or optical cable line)

-micro wave channels along transmission lines and distribution network

-loudspeaker broadcasting channel

-communication signal channel

When remote control channels are selected by using existing channels or making new ones, the requirements on reliability shall be considered carefully.

In order to utilize remote control equipment and communication channels effectively, the following measures can be adopted.

(1)Telemetry on power flow on some parallel power lines with same voltage is applied by summing up these powers

(2)Common device is used to measure the same kind of parameters on telemetry. Consequently, at load dispatching center, one meter can be applied to measure various parameters. However, in this case, these parameters shall not be transmitted simultaneously.

(3)In order to reduce volume of signals on telemetry, analog telemeters are replaced with digital signals which indicate whether measured value exceeds its limit on the parameter.

(4) In order to secure simultaneous nointerruptionof transmission of signals on telemetry and remote signals, combined remote control equipment shall be used.

Power supply source of remote control equipment are shared for devices of communication channel and remote control system.

-At the point where AC current is consumed for operation, if standby power sources areavailable at this point, individual standby source for remote control equipment is required.

-In case that the remote control system does not have standby power source, standby power source for remote control system is not required, in principle.

-At power station where battery is used as power source, standby power source for remote control

standby power source shall be operated automatically.

All remote control equipment and remote control cubicles shall be located at the places convenient for operation, and external contacts of remote control equipment shall be arranged so that secondary circuits can be connected to these external contacts.

Chapter 5-4 Secondary Circuits

Article 535. Applicable Scope

As stipulated in Technical Regulation.

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durability shall meet the following items.

-Secondary cable core connected to electrical cubicles and/or equipment by screwing shall have cross section area not smaller than 1.5mm2 (in 5A - 2.5mm2 current circuit); for unimportant secondary circuits, wires of checking circuit and signaling circuit are allowed to have cross section area of 1mm2).

-For secondary circuit with operating voltage of 100V and above, cable line which is connected by

tin soldering shall have its cross section area not smaller than 0.5mm2.

- For secondary circuit with operating voltage up to ,60Vcable line which is connected by tin soldering shall have its diameter not smaller thanmm0.5(cross section area of 0.197 2).m Communication devices and remote control equipment and similar circuits should be connected by screwing.

Connection of single core cable (by screwing or tin soldering) shall be only used in stationary parts of equipment. Connection of cable core to components of mobile equipment or by plug in (plug, connection boxes, etc.) as well as connection to electrical cubicles and equipment located in vibration

places shall use flexible multi-core cables.

Article 537. Requirements for Cross-Section, Accuracy and Mechanical Durability

Regarding the selection of the crossection of secondary circuit cable,the following requirements shall be satisfied:

1.Current transformers and operating circuit shall have accuracy:

-As mentioned in Chapter 2-6 - for meters.

-For power measuring converter to in order to have input data to computerin accordance to Chapter 2-6, as for technical meters.

-Accuracy class shall be not lower than - 3for meters at panel-board and current and power measuring converters used in measuring circuits.

-Usually, error limitation is 10% - for protecting circuit (refer to Chapter 5-2).

2.For voltage circuit, voltage loss from voltage transformer (in case that all protective relays and meters are in operation, voltage transformer is at maximum load) to:

-Electricity meter and measuring converting devices to input data in computershall not exceed 0.5%.

-Electricity meter of the line connecting power systems - shall not exceed 0.25%.

-Technical data collectors - shall not exceed 1.5%.

-Meter in panel-board and power sensor for measuring circuits - shall not exceed 1.5%.

-Protection cubicle - shall not exceed 3% (refer to Chapter 5-2).

In case that coordinating to supply electricity to the abovementionedcomponents by same cable core, its cross section area shall be selected based on minimum voltage loss value.

3.For switching current circuits, voltage loss from supply source:

-To control cubicle or unreinforced magnetic control windingshall not exceed 10%at maximal load current.

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- To reinforced magnetic control winding - shall not exceed 20% reinforced current.

4. For voltage circuits of excitation -conautrolling equipments, voltage loss from voltage transformer to measuring components shall not exceed 1%.

Article 538. Sharing Cable Cores

It is allowed to share multi-core cable for controlling, measuring, protecting and signaling circuits of AC and DC current, as well as for power circuits feeding the small consumers (e.g. motors of valves).

In order to avoid increasing reactance of cable core, it is necessary to divide secondary circuit of current transformer and voltage transformer so that in any mode, total current of such circuits in each cable line is equal to zero.

It is allowed share cable for various circuits, except standby ones.

Secondary circuits for control, protection systems voltage of 220kV or more must be physically separate.

Article 539. Cable Installation

Usually, secondary cable is connected to concentrated clampbank, however, two terminals of secondary conductors should not be connected to one screw.

It is allowed to directly connect cable to outlet of measuring transformer. Cable connected to clamps shall be corresponding to cross section area of cable core.

It is allowed extending secondary cable if cable line is longer than length of cable on cable drum of manufacturer. Connection of metal armored cables is made by closed connection boxes or exclusive clamp bank.

Non-metal sheathed cables shall be connected by mediate clamp bank or exclusive connection boxes. It is prohibited to connect secondary circuit by twisting without any welding.

other equipments, shall use conductor or cable with cross section area not smaller than:

-1.5mm2 for single core in case of connection by screw.

-0.5mm2 for single core in case of connection by welding.

-0.35mm2 for multi-core in case of connection either by welding or screwing if the core has terminal. If there is proof for operation safety, it is allowed to make connection by welding flexible cable’s core with cross section area smaller than 0.35mm2, but not smaller than 0.2mm2.

-0.19mm2 for cable core in case of connection by welding in electricity circuit with voltage not higher than 60V (panel-board, dispatch control panel, remote control equipments, etc.).

Connection of single-core cable to fixed components of equipments shall bemade by screwing or welding. Connection of cable core to mobile components or detachable components of equipments (jack or connectors, etc) should be made by flexible cable.

When connecting cable by welding, it is necessary to ensure no mechanical force at the connection joint.

In case cable shall go through entrance, it is necessary to use flexible cable with cross section area not smaller than 0.5mm2. It is allowed to use single-core cable with cross section area not smaller than 1.5mm2, provided that at the connecting point cable is twisted.

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Cross section area of conductor on equipment panel and fabricated elements is identified at the requirements on timeless short circuit protection for securing long-term load permissible currents as specified in Chapter 2-4. In addition, for circuit which comes from current transformer, it is necessary

to satisfy heat resistance requirement. Conductor and cable used shall be insulated withflame resistant material.

Equipment in the same cubicle, panel-board can be connected directly by terminals or intermediate clamps.

Terminals of circuits which can be connected to testing devices or tools, if necessary, should be arranged on clamp bank or in testing boxes.

It is necessary to equip mediate clamps in the following cases:

-Connecting conductor to cable.

-Gathering circuits with the same-name (gathering ends of tripping circuits, ends of voltage circuits, etc.).

-It is necessary to connect to mobile or portable testing, measuring devices which do not have testing boxes or similar components.

Terminal clamps of associated circuit or different devices shall be separated to the particular clamp bank.

In clamp bank, terminals of the line are not allowed to be closely placed to each other because if they touch each other it will cause fault or wrong operation.

When arranging various protective relays or various devices of the same circuit in cubicle, power supply from pole of switching circuit through concentrated clamp series as well as the allocation of circuits to different cubicles shall be operate independently from each type of protective relay or equipment. If breaking circuits of individual protective relay does not have connector, connection of these circuits to outlet protective relay or to breaking circuit ofuitcircbreaker shall be through particular terminal clamps. Then, connection of these above-mentioned circuits inside cubicle should

be carried out without depending on protective relay type.

In operation, in order to check and test protection circuit and automation, it is necessary to equip testing boxes or clamps of measuring wire terminals, ensuring not needing separation of conductor or cable from switching current source, voltage transformer and current transformer with possibility to bypass prior current.

Periodical outage of protective relays and automation equipments according to working regime of power network, conditions on selectivity or other reasons shall be performed by operators using exclusive means in order to disconnect them from operation regime.

Article 540. Cable Connection Method

As stipulated in Technical Regulation.

Article 541. Circuit Insulation

Regarding the insulation of components in secondary circuits, check of insulation of DC and AC operating circuit shall be performed on each independent source (includingisolated transformer) without grounding.

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Devices for checking insulation shall secure to send signals in case that insulation value is lower than specified values. For DC circuit, it is necessary to measure insulating resistance of poles. No need to check insulation on operating circuit without branching circuits.

Article 542. Circuit Protective Measures

Article 543. Signal Systems in the event of an Abnormal Operation or Fault

As stipulated in Technical Regulation.

Article 544. Grounding in Secondary Circuits of Current Transformers

Grounding in secondary circuit of current transformer should be carried out at the point nearby current transformer in clamp bank or on poles of current transformer.

For protection system, in case that some current transformers are connected together, grounding shall be made at only one point. In this case, it is allowed groundingthrough disruptive protective relay with voltage not over 1kV and 100ohm-resistor to release electrostatic discharge.

Secondary winding of isolated mediate current transformer is allowed not to be grounded.

Article 545. Grounding in Secondary Circuits of Voltage Transformers

Secondary coil of voltage transformer shall be grounded at neutral point or at one of terminals of winding which is required to be grounded.

Secondary winding of voltage transformer shall be grounded nearby voltage transformer, in clamp bank or on the pole of voltage transformer.

It is allowed to share grounding of secondary circuits of some voltage transformers in one distribution equipment to common grounding bars. In case that these grounding bars are connected with other distribution equipments and are located in various halls (relay cubicles of distribution equipments with various voltage levels), generally, such bars are not required to be connected together.

For voltage transformers which are AC power supply sources for operation, in case thatthere are no requirements on grounding one of poles of operating circuit, grounding for protection of secondary winding of voltage transformer shall be connected through disruptive protective relay.

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