LEGRAND LE06499AE, Instructions For Installation, Use And Maintenance Manual

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After checking the installation and ensuring that no object/tool has been left on the transformer, it is possible to close the
circuit breaker on the HV side. After energising the transformer from the HV side, close the LV circuit breaker.
6.4 Measurement of windings earth resistance
The measurement must be performed with a Megohmmeter (Megger), working up to 5000V. HV and LV terminals must
be disconnected from the electrical system, during the measurement. The measured values should be approximately as
follows:
• 5000 V for 60 s: Terminals HV / LV terminals to earth >= 20 MΩ
• 2500 V for 60 s: Terminals LV / HV terminals to earth >= 10 MΩ
If the measured values are significantly lower, dry the transformer and, if necessary, contact the after sales department.
6.5 Energising
When the transformer is connected to the electrical system, some sparkles could be visible close to the magnetic core.
This physical phenomenon does not influence the correct working of the transformer and it is not related to the quality.
If the protection systems are not correctly set, inrush current will open the circuit breaker which protects the transformer.
This can generate high voltages which can damage the windings. For this reason, it is recommended to activate the se-
cond harmonic restraint.
If the transformer has been stored for a long period, clean carefully LV and HV windings from dust, dirt and possible
condensation.
Clean the HV and LV windings from dust deposits, dirt and condensation. Use a vacuum cleaner to avoid dispersion of dirt
and dust on the transformer. Remove all condensation by drying the transformer with dry cloths and blowing hot dry air.
Make sure the room is dry, clean, with sufficient ventilation and without the risk of ingress of water.
6.3 Cleaning