Arcteq AQ-F201, Инструкция по эксплуатации

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• θ
t%
= Thermal image status in percentages of the maximum thermal capacity available
• θ
t-1
= Thermal image status in a previous calculation cycle (the memory of the function)
• I
max
= Measured maximum of the three TRMS phase currents
• I
n
= Current for the 100 % thermal capacity to be used (the pick-up current in p.u., t
max
achieved in τ x 5)
• k
SF
= Loading factor (service factor), the maximum allowed load current in p.u.,
dependent on the protected object or the cable/line installation
• k
amb
= Temperature correction factor, either from a linear approximation or from a settable
ten-point thermal capacity curve
• e = Euler’s number
• t = Calculation time step in seconds (0.005 s)
• τ = Thermal time constant of the protected object (in minutes)
The basic operating principle of the thermal replica is based on the nominal temperature rise, which is
achieved when the protected object is loaded with a nominal load in a nominal ambient temperature.
When the object is loaded with a nominal load for a time equal to its heating constant tau (τ), 63% of
the nominal thermal capacity is used. When the loading continues until five times this given constant,
the used thermal capacity approaches 100 % indefinitely but never exceeds it. With a single time
constant model the cooling of the object follows this same behavior, the reverse of the heating when
the current feeding is zero.
A AQ Q-F201 -F201
Instruction manual
Version: 2.04
111