2018/10/24 1 2018/10/24 2 SAFE DEAD WORK SAFE DEAD WORK.. What - - PowerPoint PPT Presentation

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2018/10/24 1 2018/10/24 2 SAFE DEAD WORK SAFE DEAD WORK.. What - - PowerPoint PPT Presentation

Apr 01, 2023 621 likes •908 views

2018/10/24 1 2018/10/24 2 SAFE DEAD WORK SAFE DEAD WORK.. What is this? There are two practical options.. NRS 097-2-1 compliance (switch off and break before you make) What is the Dead Grid Safety Lock?

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SAFE DEAD WORK

  • “SAFE DEAD WORK”………….. What is this?
  • There are two practical options…..
  • NRS 097-2-1 compliance (switch off and break before

you make)

  • What is the Dead Grid Safety Lock?
  • How does the Dead Grid Safety Lock work?
  • Is installation net-energy throttling functions as a safety

feature?

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Electrical Installation Regulations

Point of Supply Point of Control

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Two Points of Supply

Utility Point of Supply EG Point of Supply

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LV Dead - Safe Work Practice

  • Identify circuit
  • Open circuit
  • Isolate circuit
  • Tag circuit
  • Lock out circuit
  • ( DO NOT USE EARTHING & BONDING )
  • Test at location
  • Work

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Locked Out and Tagged

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Typical LV Locking and Tagging Equipment

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Test to Proof Voltage = 0 Volt = Safe

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Single Customers per MV-LV Transformer

  • Employ standard LV safe procedure

as given above:

  • I.e. Isolation of the installation

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Multi-Customer LV Networks

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Complex and Impossible to Employ the normal safe work procedure

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Typical Over Head LV Networks

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Where are the EG ?

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The only feasible Approach: Secure - Automated Safety Systems

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How do we automate this?

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Contactor

C NO

With the Utility side dead, a live EG cannot feed power back Simple example of one embodiment of the principle.

UTILITY NETWORK CUSTOMER INSTALLATION

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Automated LV Safe Work Practice

  • Normal upstream safety

procedure

  • Test at location + Automated

Dead-Grid Lock

  • Work

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Dead-Grid Lock The Purpose of the DEAD-GRID LOCK is to ensure that power cannot flow back from a EG once a utility worker has proofed that this part of the LV network is safe to work on. It relies on the EG to power down automatically when the utility power fails. ( Anti-islanding and out of bounds requirements)

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Dead-Grid Lock If this does not happen, the safe work procedure will detect the condition and further steps is to be taken to make the installation safe. The sole purpose of this device is to secure that once the network is proven to be safe to work on- that it remains so, regardless of any actions or failure of equipment during this time on the EG’s side.

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Test to Proof Voltage = 0 Volt

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The Critical Step : Test – once dead AND Utility supply locked

  • ut –

The automatic Dead Grid Safety Lock ensures safety from the EG’s side.

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Cable to EG

On / Off AC Disconnector

Dead-Grid Safety-Lock

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Dead-Grid Safety-Lock

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8.9 kVA On PF .98

DC side Arresters

PV String Installation

Main DB Connection

Inverter

DGSL Installation on a PV Inverter

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Safe Even when it is DEAD

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LV Live - Safe Work Practice

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Multi customer feeder - Minimum Safety Requirements

MAIN DB POS POC Locked in Grid-Tied-Mode EG - DB PE PE

Structural lighting protection and bonding of PV panels