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DESCRIPTION
The Electrical
Variable Analyzer Relay (EVAR) has been designed to continuous
monitoring of a single or three-phase system. It provides
metering for current, voltage, real power, reactive power,
apparent power , energy use, cost of power, power factor and
frequency. Programmable setpoints and 3 assignable output
relays allow control functions to be added for specific
applications. This includes protection on over/under current
or voltage, unbalance current or voltage, frequency, power,
power factor, demand and THD. With the harmonic analysis, any
phase current or voltage can be displayed and the harmonic
content calculated. The different functions provided by the
EVAR may be classified into the following groups:
Applications:
- Electrical variable analyzing
of feeders, capacitor banks, transformer, generators and
motors.
- Medium and low voltage 3 phase
systems in sites commercial, industrial and utility.
- Power quality analysis.
- Flexible control for demand
load shedding, power factor, etc.
Protection:
- CT primary ratio selectable in
5 amp steps (1 A to 5000 A).
- Setpoints for alarm or control
from most measured values including:
Phase undercurrent and
overcurrent
Neutral overcurrent
Undervoltage and Overvoltage
Current and voltage unbalance
Volts phase reversal
Average current and voltage THD
Underfrequency and Overfrequency
Positive and negative real power
Positive and negative reactive power
Power factor lead and lag.
Demand: current per phase (A), real power (KW), reactive
power (KVAR) and apparent power (KVA).
- 3 assignable output relay.
- Loss of control volts relay.
- 4 switch inputs from
external devices for flexible control configuration.
Digital
Measurement:
- RMS line and ground currents.
- RMS line and phase voltages.
- Active power (KW), reactive
power (KVAR) and apparent power (KVA).
- Active energy (MWhr) and
reactive energy (MVARhr).
- Power factor and system
frequency.
- Positive and negative real
power (KW) and reactive power (KVAR).
- Running and maximum demand:
current per phase (A), real power (KW), reactive power (KVAR)
and apparent power (KVA).
- Current and voltage unbalance.
- Harmonic analysis up to even
(11) for power quality review and problem correction.
- Event recorder.
Signaling and
Programming:
- LED and LCD display
indication.
- Touchpad programming.
- Indication and storage of
fault conditions and their values.
- Indication of the status
system (normal, current fault, voltage fault, unbalance
fault, frequency fault, power fault, power factor fault,
demand fault, THD fault).
Communication:
- Remote digital communication
to a PC or PLC, via RS422 or RS485.
- Remote adjustment of
protection and relay characteristics.
- Storage of faults and events
for further statistical treatment.
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