NDBU-95C 64008366D NDBU95C for optical fiber adapter ABB

Description

• NDBU-95C The analog input used to sense tap position is programmed with the S2 SYSTEM SETUP 

  ONLOAD TAP CHANGER setpoints.

   To verify the operation of this circuit, connect a variable resistor across

  terminals A3 and A4.

  The resistor range should cover the full range of resistance produced by

  the tap changer mechanism. The tap position is NDBU-95C displayed in A2

  METERING  TAP CHANGER  TAP CHANGER POSITION.

   Adjust the resistance to simulate the minimum tap position and verify

  that a “1” is displayed.

   Gradually increase the resistance up to the value which represents the

  maximum tap value, verifying that the tap position indicator tracks the

  resistance.

• 
• Keep track of modifications/changes made to settings during the course of these

  commissioning steps and ensure that all settings are returned to the ‘in-service’ values

  at the end of the tests.

  7.5.2 Harmonic Restrained Percent Differential

  7.5.2.1 Description

  The harmonic restrained percent differential NDBU-95C element setpoints are located in S4 ELEMENTS

   DIFFERENTIAL  PERCENT DIFFERENTIAL. Disable all other protection elements to

  ensure that trip relay(s) and auxiliary relays are operated by element under test only. With

  a multimeter, monitor the appropriate output contact(s) per intended settings of the

  FlexLogic™. Refer to the relay settings to find out which relay(s) should operate when a

  given element operates.

  7.5.2.2 Minimum Pickup

  The minimum pickup of the phase A element is measured by applying a fundamental

  frequency AC current to terminals H1 and G1, winding 1 phase A. Monitor the appropriate

  trip and auxiliary contact(s) as the current is increased from 0 A. Compare the current value

  at which operation is detected against NDBU-95C the S4 ELEMENTS  DIFFERENTIAL  PERCENT

  DIFFERENTIAL  PERCENT DIFFERENTIAL PICKUP setpoint. Since the operating point is

  normally set quite low, fine control of the current signal will be required to obtain accurate

  results.

  The currents in the winding may be phase shifted or may have the zero-sequence

  component removed due to auto-configuration (see Auto-configuration on page 5–6). As

  an alternate to calculating to relation of input current to differential current, the differential

  current is displayed in A2 METERING  CURRENT  DIFFERENTIAL. Ensure that the

  displayed value is the same as the minimum pickup setting when the element operates.

   Check that the Trip and Message LEDs are flashing and one of the

  following trip messages is displayed:

  LATCHED a: Percent Differential, or OPERATED a: Percent

  Differential

  Note

  The above messages will indicate either OPERATED or LATCHED depending on the S4

  ELEMENTS  DIFFERENTIAL  PERCENT DIFFERENTIAL  PERCENT DIFFERENTIAL

  TARGET setting.

  To independently verify that auto-configuration causes NDBU-95C the currents to be as measured,

  follow the rules outlined in the steps below.

   Look up transformer type in Table 5–1: Transformer types on page 5–

  13.

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