EXCOUNT-II: User’s manual

This symbol is a visual warning to prevent errors that could result in material damage and/or failure of the EXCOUNT-II Surge Arrester Monitor. As a quick guide, the appropriate procedure in the table below should be followed to install EXCOUNT-II safely and correctly.

Before Installation

Inspection upon arrival
Tools for assembly
Insert the 9V battery in the transceiver
Pre-installation
Installation of battery in the sensor
EXCOUNT-II Software

Installation
Using the software
Installation of USB drivers

First time administration of the sensors
Once at site, individually check that it is possible to make contact with each sensor prior to installation, as described in section 2.4 e

For convenience, a Philips screwdriver is provided to fit the 9V battery into the transceiver. The preparations are now done and you can proceed with the installation of the EXCOUNT-II sensor on the arrester.

Sensor Installation

Safety information

Note the sensor ID number
Common installation alternatives
Section 3.4)
Section 3.5)
Section 3.6)
Section 3.7)

Reference measurement
Installation of sensor alternative 1

Before installation, note the sensor ID number along with the corresponding tap station, position, phase and type. The sensor is too far from the surge arrester field, so the only option is to charge the internal power source via solar cells (or a separate DC battery). Special attention must be paid to placement and some configurations (such as tall towers) may require a separate antenna (available as an option).

Special attention must be paid to the arrangement, especially if resistive current measurements are to be made. After completing the installation of the sensor and energizing the arrester, a complete set of measurements should be made for reference and then transferred to the computer software as described in section 5 of this manual. Mount the EXCOUNT-II sensor to either the pre-assembled coupling, figure 3.6.1, or to the pre-assembled terminal, figure 3.6.2, as appropriate for the type PEXLINK transmission line arrester.

The assembly of the components is generally as in section 3.4 alternative 1, except that the arrester is specifically intended for reverse mounting. Furthermore, it may be necessary to mount the EXCOUNT-II sensor "upside down" in certain cases, as shown in Figure 3.7.1.

Using the transceiver

Important information

Transceiver functions

Use of external hand-held antenna

Transceiver symbols
Flowchart, making measurements
Sychronization of the clocks
Range of the communication
Your body affects the signal strength
Optimal direction of the internal transceiver antenna
Direction of the sensor antenna
Special configurations

Tower and Gantry layout

Total versus Individual readings
Measurement strategy

A separate external handheld antenna is available as an option for use in special applications that require greater signal strength than is possible to achieve with the receiver's internal antenna. Turn on the transmitter and enable the external antenna from the settings menu as described in section 5.4.2. d) Take measurements, following the instructions given in section 4 of this user manual. After completing the measurements, carefully remove the external antenna and place the protective cover on the transmitter. f).

Direct and completely unobstructed line of sight is preferred between transmitter and sensor during communication. The signal strength between the antennas on the transmitter and sensor is affected by their orientation relative to each other. Note that the best reception and maximum range is achieved by pointing the transmitter at approximately right angles to the sensor.

Often it is sufficient to take a few steps to get out of the “dead zone” before transmitting again, to establish contact between the transceiver and the sensor. During communications, a direct and completely unobstructed line of sight between the transceiver antenna and the sensor is preferred.

Transceiver menus

Main menu

Transfer data

E ABB
Data transfer from PC to Transceiver In this mode, Sensor ID’s can be transfered from the PC to the
Data transfer from Transceiver to PC In this mode data collected from the Sensors can be

Battery check

Leakage current measurement Select sensor ID to read data from with the
Read surge counter data Select sensor ID to read data from with the key

Settings menu Select alternative with the key

External antenna By default internal antenna is enabled
Set contrast
Set clock and date

Transferring data from a PC to a transceiver (see 5.1.1) Transferring data from a transceiver to a PC (see 5.1.2) Back to the main menu. Each time the battery is changed, the time and date of the transmitter must be checked and synchronized with the PC (see 4.4) before data transfer or measurements are taken. Successful download is marked with Unsuccessful download is marked with If the download was not successful, an error code is displayed.

When the correct date and time are set, move the cursor to X and enter the value with.

Surge arrester monitoring theory

Introduction

The increasing demand for improved power supply reliability and lower maintenance costs has increased attention to condition monitoring of equipment in high-voltage substations. The voltage on the arrester in terms of the intensity and frequency of impulse currents. The first aspect is addressed by continuously counting current peaks and the second by regularly carrying out leakage current measurements.

The EXCOUNT-II is designed to handle both surge counting and leakage current measurements in a single monitoring system. The EXCOUNT-II system consists of a sensor permanently mounted to the base of the arrester, a transceiver for wireless communication with the sensor, and proprietary software installed on a personal computer. In the following, the bases for surge counting and leakage current measurements are described, and the corresponding functions of the EXCOUNT-II are presented.

For general information on the various diagnostic methods for metal oxide arresters, see IEC 60099-5.

Surge counting

The measured peak current values are listed in five pulse current intervals and stored in the EXCOUNT-II memory along with the date and time of each pulse. The accuracy of impulse current measurements is optimized with respect to lightning current impulses. The EXCOUNT-II memory stores information for the most recent 1000 pulses, at a maximum rate of 2 pulses per second.

The contents of the memory are transferred to the EXCOUNT-II transceiver during the leakage current measurements described below. The surge counter data is later transferred to a PC and analyzed using EXCOUNT-II software. The use of the detailed surge count information provided by EXCOUNT-II is not limited to arrester voltage estimation.

The information can also be used to analyze the occurrence of the last 1000 lightning surges in terms of date, time and amplitude of the arrester impulse current.

Leakage current measurements

The resistive leakage current is defined as the maximum value of the resistive component of the leakage current, i.e., in the leakage current region, the resistive current depends on the voltage stress and the temperature of the varistors. As an example, the third harmonic content of the total leakage current is typically 10-40% of the resistive current.

The harmonic content of the total leakage current can therefore be used as an indicator of the resistive leakage current. Theory of surge arrester monitoring The total leakage current is measured using the zero flux. The resistive leakage current level (optional) is calculated in two steps: First, the resistive third harmonic of the arrester resistive leakage current, with compensation for the third harmonic in the voltage, is determined by the equation below (for a three-phase horizontal installation) .

The ratio of the total resistive leakage current to the third harmonic current depends on the stress of the operating voltage (the operating voltage divided by the rated voltage) and the temperature of the arrester (in practice, the ambient temperature). Therefore, these parameters are recorded at the time of measurement of total leakage current and field probe current.

Radio transmission protocol

Packet communication protocol

Nearly all short-range wireless data communications use some form of packet protocol to automatically ensure that information is received correctly at the correct destination. A packet typically contains a training preamble, a start symbol, routing information (to/from, etc.), a packet ID, all or part of a message, and error detection bits. The structure starts with a training primer, which improves the detection of weak signals at the receiver by 'training' the data slicer for the best noise immunity and by providing signal transitions to train the clock recovery process.

The preamble is followed by a start symbol (often called a start vector), which is a distinct pattern of bits that marks the start of the packet's information section. In the EXCOUNT-II protocol, the packet ID is followed by message size or status information. The following two bytes of the packet include a 16 bit error control code (frame check sequence), based on the X.25 packet standard (ISO 3309).

The error check code is recalculated at the destination to confirm error-free detection. The ISO 3309 frame check sequence provides very high error detection assurance for packets up to 256 bytes in length.

Technical data

Necessary arrester condition during leakage current measurement Transient leakage currents can affect the measurements performed. To ensure both stable readings and the best possible consistency for comparison between measured values, leakage current measurements should not be taken while it is raining or otherwise when large external leakage currents on the house can be expected. This is less of a problem for arresters with silicone housings, as such external leakage currents are lower. conditions Sealed, waterproof design, IP67.

Built-in solar cell and field probe Backup 9 Volt lithium battery U9VL (primarily for indoor use). The surge count timestamp is only as accurate as the value stored in the sensor.

Dimensions

Disposal

When items containing EXCOUNT-II are removed from service, components must be disposed of in accordance with local regulations.

Transceiver error codes

The system voltage is too low to generate sufficient current in the field probe in the sensor. a) the line is validated correctly. The system voltage is too high and generates excessive current in the field probe in the sensor. a) the line is validated correctly. 61 Low leakage current The measured leakage current is too low (< 0.2 mApeak).. a) the line is correctly energized.

62 High leakage current The measured leakage current is too high (> 12 mAp). a) the line is correctly switched on. When the energy in the sensor drops below a certain level, the sensor disables the listening function (to save energy for recording) until the energy level is again sufficient for communication. If unexplained difficulties occur during communication, it is suggested to wait another time to make measurements or else install a 9V battery in the sensor.

When the energy in the sensor drops below a certain level, the sensor turns off the listening function (to save energy for recording) until the energy level is again sufficient for communication. If unexplained problems occur during communication, it is suggested to wait until another time to take measurements or else install a 9V battery in the sensor.

Index

Administration 20 arrester data 20

Cleaning 32 D