NR TPWS/TGN/018 ISSUE 1 PDF

Permanent installations of the following TPWS equipment are covered by this Technical Guidance Note:

• Thales Communications UK (TCUK) TPWS track sub-system equipment, as detailed within Network Rail Product Acceptance Certificate No. PA05/00446 [3].

• TCUK Self-Powered TPWS Overspeed Sensor System (SPOSS) equipment, as detailed within Network Rail Product Acceptance Certificate No. PA05/01615 [4].

The scope of this Guidance Note does not apply to the following TPWS installation configurations or items associated with the TPWS track sub-system:

• TPWS Installations at Radio Electronic Token Block (RETB) Token Exchange Points¹

• Portable TPWS Equipment for use at Temporary Speed Restrictions²

• NRS Ltd. TPWS Failure Indication Units (Master and Slaves Units)³

• NRS Ltd. 24V d.c. to 12V d.c. Converters for the TPWS Failure Indication Units³

• UPS Ltd. Uninterruptible Power Supply for the TPWS track sub-system equipment⁴

Note 1: The earthing arrangements for the TPWS equipment associated with RETB Token Exchange Points are identified within TPWS Technical Instruction No. 38 [5].

Note 2: The Portable TPWS equipment for use at TSRs is currently under development and is specified to not require a connection to earth.

Note 3: These items are constructed as Class II insulated equipment and are not earthed.

Note 4: The Uninterruptible Power Supply (UPS) for the TPWS track sub-system equipment also requires an earth connection for electric shock protection. This is associated with the 230V a.c. mains supply to the UPS, and is outside the scope of this document. Guidance on the installation of the UPS is provided within TPWS Technical Guidance Note No. 12 [6].