Timed Trip Block Feature

This feature allows a user to block protection elements from tripping indefinitely or for a user configurable time after a current based protection pick up whilst the Block Control remains set. This delay applies if the Trip 1 curve or single shot curve is active. If configured, the means to enable or disable blocking can be by Protocol Control, OCP, QAK, Custom Logic Output, IEC 61850 Control or by IOEX input.

The user can elect to block the trip indefinitely while the control is enabled or to helps to prevent tripping for a user configurable time after a pickup while the block control is enabled.

If a user time is configured and the block is enabled, a trip request is blocked from the time the pick-up commences until the block time expires. If the calculated trip time exceeds the block time, the block time has no effect. If the block time exceeds the calculated Trip Time, the block time acts as a minimum time modifier. If the current drops below the pick-up threshold, the trip block timer is reset.

Separate configuration options are provided for Phase, Earth, SEF and NPS elements on a per group basis. In addition, options are provided to block only Definite Time and Inverse DefiniteMinimum Time (IDMT) elements, or instantaneous elements or both for all four elements on a per group basis.

The Timed Trip Block feature must be made available via the Feature Selection page of WSOS5, under Protection category. Refer Figure 120.

Figure 120
Timed Trip Block feature selection page

The WSOS5 configuration options for the Timed Trip Block feature are outlined below.

Figure 121
Timed Trip Block settings page

• Block Instantaneous:

  • When configured and enabled, only the instantaneous element is blocked when Trip 1 or single shot is active. Instantaneous can be selected as the only curve or as an overlay on an IDMT curve and either would be blocked. The behavior of IDMT and Definite Time elements is not affected by this setting.

  • The Block can be enabled/cleared by Protocol Control, OCP, QAK, Custom Logic Output, IEC 61850 Control or by IOEX input for each protection type individually.

  CAUTION
  HAZARD OF UNINTENDED EQUIPMENT OPERATION User must make sure remote blocking is limited to definite times or limit usage only for the validation or pre-commissioning stages. Failure to follow these instructions can result in injury or equipment damage.

• Block IDMT/Definite Time:

  • When configured and enabled, IDMT and Definite Time elements are blocked when Trip 1 or single shot is active. The behavior of instantaneous elements or instantaneous elements overlaid on an IDMT curve is not affected by this setting.

  • The Block can be enabled/cleared by Protocol Control, OCP, QAK, Custom Logic Output, IEC 61850 Control or by IOEX input for each protection type individually. Refer to the CAUTION message above.

• Block Time:

  • If enabled and configured, single shot or protection trip 1 IDMT or Definite time and/or instantaneous Trip requests will be blocked for the selected element for the user configured time or indefinitely if set to Trip Blocked by Control. If set to a configured time, and if the Block Control is enabled, the timer commences upon a pick-up and tripping is no longer blocked after the time expires. The block time acts as an effective minimum time to the configured Trip time. The configurable Block time is 10 ms...5000 ms.

  • Note that the block is active for the first trip or single shot trip.

  • The Timer is reset if the current drops below the pick-up threshold. This means that if the protection element does not reset and if it picks up again, then as the protection element has already timed out, another trip request will be blocked for the duration of the Timed Trip Block setting. If a user time is configured, a trip request is blocked from the time the pick-up commences until the Block Time expires. If the calculated trip time exceeds the block time, the block time has no effect. If the block time exceeds the calculated Trip Time, the block time acts as a minimum time modifier. If the current drops below the pick-up threshold, the trip block timer is reset.

These digital control points are available and can be set/cleared by Protocol Control, OCP, QAK, Custom Logic Output, IEC 61850 Control or by IOEX input.

• This feature can be configured for IDMT and Definite Time Elements and/or Instantaneous elements.