Artesis AMT Toolkit, Руководство пользователя

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Equipment Faults, Diagnosis and Reporting
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measured in a unit called Volt-Amps-Reactive (VAR), rather than Watts. Reactive power
makes no contribution to the active power, so it cannot be utilized. The results of reactive
power are the costs for the work it involves and transmission losses. Therefore, utilities may
measure reactive power to financially penalize customers with low power factor loads. This
is particularly relevant to customers operating highly inductive loads such as motors at
water pumping stations.
Voltage (Vrms) and Current (Irms): The RMS (root mean square) values, Vrms (Volt) and
Irms (Amp) are the effective values of a phase voltage and a phase current. It is the
equivalent steady DC (constant) value that gives the same effect. Software gives the values
for the r phase of voltages and the r phase of currents. All three phases are displayed when
they are plotted. Operation of a motor at voltage levels above and below the name plate
values are not recommended and adversely affect the life of a motor. Software alerts the
user when the voltage level is 10 % above or 10 % below the nameplate value. Similarly,
operation of a motor at a current level above the nameplate value may cause hot spots that
decrease the insulation system rating and its life span. Therefore, motor operation above
the nameplate value is not recommended. Software alerts the user when the current level
exceeds 10% of the nameplate value.
Frequency: The rate of changing direction of an alternating voltage or current is called the
frequency and it is measured in hertz (Hz), which is the number of forwards backwards
cycles per second. Software gives this value for information purposes and there are no
upper or lower limits used for this value.
Harmonic Distortion: Harmonic distortion is the change in the waveform of the supply
voltage from the ideal sinusoidal waveform. It is caused by the interaction of distorting
customer loads. Its major adverse effect for induction motors is the heating in the stator
windings. The total harmonic distortion (THD) of the supply voltage is a measurement of the
harmonic distortion present and is defined as the ratio of the sum of the powers of all
harmonic components to the power of the Fundamental frequency. It is recommended that
operation of equipment should be less than 5% THD present in the supply voltage. Software
alerts the user if the THD is greater than 5%.
Voltage Unbalance: Unbalanced voltage will result in unbalanced currents on the order of 6
to 10 times the voltage unbalance. Consequently, the temperature rise of the motor
operating at a particular load and voltage unbalance will be greater than for the motor
operating under the same conditions with balanced voltages. In addition, the large
unbalance of the motor currents will result in non-uniform temperatures in the motor
windings. Voltages should be evenly balanced as closely as possible. Software alerts the
users when the voltage unbalance exceeds 2%.