Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 12 Page 50 of 265
3.7.4 Fitting Two HPU
If the total lamp load exceeds 20A or more than 3 LSLS cards are required, then two
transformers and two HPU are fitted and the following options are available:
Cabinet
HPU1 & HPU2
Option 1 Option
2
Option
3
Primary
Cabinet
(20A)
20A
HPU1 PL4 LSLS 1 LSLS 1 LSLS 1
HPU1 PL6 LSLS 2 LSLS 2 –
HPU1 PL7 LSLS 3 – –
Expansion
Cabinet
(20A)
20A
HPU2 PL4 LSLS 4 LSLS 3 LSLS 2
HPU2 PL6 LSLS 5 LSLS 4 LSLS 3
HPU2 PL7 LSLS 6 LSLS 5 LSLS 4
Cabinet
HPU1 & HPU2
Option 4 Option
5
Primary
Cabinet
(40A)
20A
HPU1 PL4 LSLS 1 LSLS 1
HPU1 PL6 LSLS 2 –
HPU1 PL7 – –
20A
HPU2 PL4 LSLS 3 LSLS 2
HPU2 PL6 – LSLS 3
HPU2 PL7 – –
Table 8 – LSLS Connections to two HPU
IMPORTANT: LSLS 1 must always be connected to PL4 of HPU1.
The allocation of LSLS cards to HPU 1 or HPU 2 is done so that, as far as possible,
the total load is distributed evenly across both transformers and HPU, and in no
event does the current drawn from either HPU 1 or HPU 2 exceed 20A; this includes
regulatory signs but excludes short-term red/amber periods.
Note that the number of LSLS cards connected to HPU1 or fitted in the Primary
cabinet can be 1, 2 or 3; HPU1 and the primary cabinet do not need to be filled
before moving to HPU2 and optionally an expansion cabinet. Also see section 3.13
on page 54 for limits on the number of LSLS cards that can be supported by the
controller.