Artesis AMT Toolkit, Руководство пользователя

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Appendices
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7.2. Appendix 2: Current and voltage transformer selection
Voltage transformers and current transformer must meet local standards and
regulations. For North America, current and voltage transformers must be certified
by an OSHA appointed NRTL to appropriate UL or CSA - product safety standards.
When selecting a current transformer, both the maximum current the motor will
handle in practice and the type of motor drive used should be considered. Systems
employing an inverter will generally limit initial inrush to a maximum of about 150%
of nominal current.
With a soft-starter system this limit will probably be 400%. Transformers must be
able to withstand the maximum expected inrush currents and should be selected
accordingly.
Transformers should be selected such that the nominal motor values for current and
voltage are minimum 70% of the corresponding sensor rating Failure to do so will
result in a loss of sensitivity and the ability of AMU to detect motor degradation or
change.
Current transformers should be 1% accurate or better. The secondary current
should be either 5A for 5A AMU units or should be 1A for 1A AMU units. The
secondary of the current transformer has to be SELV.
Current transformers frequency should be selected according to output frequency of
the inverter driven system. Output frequency has to be within the range of current
transformers’ frequency.
Voltage transformers should be 1% accurate or better with 100V, 110V, or 120V
secondary voltage.