ABB original inverter drive unit NDCU-21C NDCU-21 NDCU-21C-02 brand new

Description

• NDCU-21C For the phase shift for the particular set of vectors, determine the

  processing applied to the current vectors for that winding from Table 5–

  2: Phase shifts on page 5–24.

   Calculate the “dashed” current values NDCU-21C using the equations in Table 5–2:

  Phase shifts on page 5–24.

  If applicable, use the zero-sequence removal computation. This is

  applicable for all Delta windings and for both windings of a wye-wye

  transformer. Compute the processed current vectors to obtain the

  “dashed” values for that winding.

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   Calculate the CT correction factor for windings 2 (and 3 if applicable)

  and apply as necessary.

   Turn the equations around to compute the threshold differential currents

  in terms of the applied currents.

  Note

   To check the threshold without NDCU-21C performing computations, inject

  balanced 3-phase currents into any winding.

  With balanced conditions, there is no effect on magnitude due to phase

  shifting and zero-sequence removal has no effect. However, the CT ratio

  mismatch is still applicable.

   Repeat the minimum pickup level measurements for the Phase B (inputs

  H2 and G2) and the Phase C element (inputs H3 and G3).

  The above tests have effectively verified the minimum operating level of the three

  harmonic restrained differential elements. If desired the above measurements may be

  repeated for the phase inputs for the other winding(s). The results should be identical.

  7.5.2.3 Verification of Local Reset Mode

   Set the differential element with a NDCU-21C latched target.

   Apply enough current to cause the relay to operate, then remove the

  current.

  The Trip LED and the Phase LED should be latched on.

   Set S1 745 SETUP  RESETTING  LOCAL RESET BLOCK to Disabled.

   Press the RESET key. The target should reset.

   Set S1 745 SETUP  RESETTING  LOCAL RESET BLOCK to Logic

  Input 1(16).

   Press the RESET key and verify that the target does not reset if the

  logic input is not asserted.

   Verify the status of selected logic input through the A1 STATUS 

  LOGIC INPUTS  LOGIC INPUT 1(16) STATE actual value.

   Assert the selected logic input, apply NDCU-21C the current to cause the target to

  latch and verify that pressing the RESET button does not reset the LED.

  The following message should appear: INVALID KEY: MUST BE IN LOCAL

  MODE.

• Verification of Remote Reset Mode

   Set the differential element with a latched target.

   Apply enough current to cause the relay to operate, then remove the

  current.

  The Trip LED and the Phase LED should be latched on.

   Set S1 745 SETUP  RESETTING  REMOTE RESET SIGNAL to Logic

  Input 1(16).

   Assert logic input 1.

  The target should reset.

  7.5.2.5 Verification of Solid-state Output

  If the solid-state Output Is Used To Drive Auxiliary Relays,

   Verify that these relays operate whenever the relay is in a trip condition.

   Ensure that the current though the auxiliary coils is interrupted by an

  external contactor between each test.

  To avoid operating the breaker during the commissioning process when the solid-state

  output operates the breaker directly,

   Use the circuit shown below to verify this output.

  Whenever the relay is in a trip state, current flows through the load

  resistor.

   Select the resistor for approximately 1 × CT of DC current with the

  normal DC supply voltage used in your relay scheme.

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