Description Of Operation; Introduction; Operation - ZIGOR FIEM Serie Manual De Operación

Operating Manual
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DESCRIPTION OF OPERATION

2.1 Introduction

The 20kVA FIEM and 50kVA FIEM are products which have been designed essentially to improve the
quality of the electricity supply of BSs (Base Stations) four cellular telephony connected to a 25kV
catenary via a single phase transformer of 20kVA and 50kVA respectively, reducing to 230 V. The FIEM
carries out two basic operations: The first one consists of establishing the efficient voltage value from an
electromechanical regulation system and the second consists of eliminating frequent overvoltages
caused by recurrent connection and disconnection operations or changes in the consumption regime of
the different consumptions of the catenary.
The FIEM is, therefore, a stabilisation system that offsets (Stabiliser) voltage regulation problems in the
25kV line and a non-destructive energy spike absorption system (Incremental Filter).
The Stabiliser is based on the basic principle of the adding or subtracting voltage in accordance with the
supply voltage. This correction is made with a motordriven Variac, controlled by an electronic board that
reads the grid voltage at all times and makes the corresponding corrections in order to guarantee the
correct use of a voltage.
The Incremental Filter of the FIEM operates when it detects a positive voltage derivation (higher in value
to the nominal voltage of the grid). The faster the voltage increases the impedance is lower. It has a
virtually unlimited number of operations and placed in parallel, the energies absorbed are distributed
equally. It can then amplified in accordance with the magnitude of the disturbances.
The chapter on operation (3) provides a detailed description of the Stabiliser and Incremental Filter.
The FIEM is a protection system that works in addition to protection systems against overvoltages not
caused by line operations or regulating problems, such as direct lightning discharges (distant),
electromagnetic pulses, etc. For these, other protections are recommended. These are usually required
and used in the protection chain from generation, through transport and distribution to the equipment
protection level.

2.2 Operation

The following figure shows the general diagram of the FIEM and identifies the Stabiliser, Incremental
Filter and Load Contactor.
The FIEM consists of the following:
•
An electromechanical stabiliser to stabilise the input voltage with its associated control.
•
One or two incremental filters to absorb the power spikes from the grid. The number of filters
(one or two) will depend on the amount of power it is wished to absorb. Each filter will be fitted
with its own electronics.
•
A load contactor in order to connect the load to the stabilised and filtered grid.
•
Auxiliary electronics control the load contactor. Moreover, it is responsible for managing three
alarms generated by means of potential free contacts.
The FIEM monitors the grid voltage in the unit to be protected. In the case of any level of this magnitude
that exceeds the expected values, the FIEM acts simultaneously to stabilise slow voltage variations (12
volt / sec.) and absorb rapid voltage transitories (of up to 1200 Jules in the grid connection), preventing
these from going on to the load.
© ZIGOR
20/50kVA FIEM
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