Appendix Ii - Parameter Calculations - Ametek TR-2100 Operation Manual

TR-2100 User Manual
Appendix II – Parameter calculations
Introduction
The Multi Function Recorder (TR-2100) is a very high performance monitoring instrument
that can implement the functions of over 12 different systems concurrently. These can be
configured and interrogated locally or remotely over a dial up modem or corporate WAN.
Inputs are connected to standard VT and CT secondaries as well as relay and switchgear
auxiliary contacts. For the CT signals, an interposing shunt resistor, 'wedding ring' or clamp
type CT can be used. Derived quantities (frequency, sequence components, power etc.) are
computed internally and no external transducers are required. External transducers can be
used for other, non derived, quantities such as temperature, pressure, generator rotor angle,
etc.
Up to 32 analog inputs are synchronously sampled at regular intervals up to 195,000
samples per second, at 16 bits per sample. The sample clock is derived from a conditioned
oscillator, which is phase locked to a 1 PPS signal from a GPS receiver. It is organized such
that the TR-2100 will always take a sample at the exact second marker.
Conventions
The TR-2100 uses mostly fundamental calculations due to the differing techniques for
computing derived quantities (especially power), and the lack of world wide accepted
standards (such as parameters computed from the current and voltage vectors at the present
system frequency). Therefore, power factor is actually displacement power factor (not true
power factor) in most cases.
Reactive power into an inductive load (current lagging voltage) is treated as positive.
Exported real power (voltage and current in phase) is treated as positive.
Phase to neutral vectors are shown pointing outwards from the neutral point. Phase to phase
vector Vab is shown pointing from a to b; i.e. It is the resultant vector of Vb - Va.
Three voltage or current channels can be defined as a phase group. These are listed in
positive sequence order and the first channel is the reference phase. One voltage and one
current phase group can be defined as a line group. These groups are used when defining the
sources for sequence component, power & impedance calculations, etc.
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