Eaton EDR 3000, Installation, Operation And Maintenance Manual

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EDR-3000 IM02602003E
TIS X – Phase and Sensitive Ground Current Measuring Card
The sensitive ground current measuring card is provided with four (4) current measuring inputs: three for measuring the
phase currents and one for measuring of the sensitive ground current (The sensitive Ground current Input has different
technical data. Please refer to chapter Technical Data.).
The input for ground current measuring either can be connected to a zero sequence current transformer or,
alternatively, it is possible to connect the summation current path of the phase current transformer to this input (residual
connection).
Current transformers have to be earth grounded on their secondary side.
Interrupting the secondary circuits of current transformers causes hazardous
voltages.
The secondary side of the current transformers have to be short circuited
before the current circuit to the device is opened.
The current measuring inputs may exclusively be connected to current
measuring transformers (with galvanic separation).
Make sure that the tightening torque is 17.7 In-lb [2 Nm].
Do not interchange the inputs (1 A/5 A)
Make sure the transformation ratios and the power of the CTs are
correctly rated. If the rating of the CTs is not right (overrated), then the
normal operational conditions may not be recognized. The pickup value
of the measuring unit amounts approx. 3% of the rated current of the
device. Also the CTs need a current greater than approx 3% of the
rated current to ensure sufficient accuracy. Example: For a 600 A CT
(primary current) any currents below 18 A cannot be detected any more.
Overloading can result in destruction of the measuring inputs or faulty
signals. Overloading means that in case of a short-circuit the current-
carrying capacity of the measuring inputs could be exceeded.
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