ELV – The total solution?
Copyright © Siemens plc 2009. All rights reserved.
The growth of ELV traffic systems
ST900 ELV system launched to
great acclaim at Traffex 2007
The benefits of ELV traffic systems
 Controller
 Signal heads
 Pedestrian street furniture
 Increased electrical safety
 Also potential for reduction in use of
ladders
Offered the first realistic opportunity
for wide scale deployment of
complete ELV systems ‘on-street’
 Lower installation costs
Delivered many benefits compared
with existing LV solutions
 Reduced carbon footprint
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 Often reduces significantly the
number of street cables required
 Helios ELV signals consume 80%
less power than their incandescent
equivalents
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ST900 development challenges
The ‘ELV Project’ started over two
years earlier in 2005
Was initially intended to be just a
minimal update to the ST800
 Simply change the lamp switches
to work at 48V!
Detailed research showed that this
would not yield the best solution
 Voltage losses in the system
would limit street cable lengths
 Future reduction in LED signal
power would be difficult to manage
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ST900 development challenges
A new concept was needed,
resulting in a revolutionary design
employing a ‘DC’ lamp supply
ELV drive and monitor schematic
Enabled the use of FET switches
 Reducing variable voltage loss in
the controller by 80%
Facilitated the improvement of
accurate lamp current monitoring
 Essential to cope with reducing
LED signal powers
Controller was also to be
designed to be compliant with
CLC / TS 50509
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Star Earth at
controller
Over current
detection
Residual
current
quench
FET switch
Dual
channel
current
monitors
Dual
channel
voltage
monitors
Repeated for
each of 32
outputs per
Lamp Switch
-48V
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UK / Industry / Mobility / Traffic Solutions
The benefits of compliance with CLC/TS 50509
Unlike incandescent lamps,
modern LED signals are very
tolerant of varying supply voltages
 Light output is maintained over
very large voltage swings
But they have a defined voltage at
which they will switch to dim
Signals may incorrectly switch to
dim if their supply voltage falls too
low!
 During times of low mains supply
coupled with long cable runs
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The benefits of compliance with CLC/TS 50509
33V
Guaranteed
Dim
27.5V
 Up to 250M in the ST900 ELV
15V
Maybe Dim
or Off
Guaranteed
Off
LED signal limits
as defined by
CLC/TS 50509
Excessive cable run
Maybe Bright
or Dim
22V
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Signal may dim incorrectly
38V
 Allows longer cable runs
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Signal stays bright
Guaranteed
Bright
48V
Long cable run
This simple solution allows more
voltage to be lost before the signals
begin to experience false dimming
58V
Signal stays bright
 57% of bright supply compared
to 66%
Effects of excessive volt drop
Short cable run
CLC / TS 50509 sets a lower dim
threshold than defined for LV based
systems
Supply voltage as seen by
the LED signal
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The growth of ELV traffic systems
The technical innovation embodied
in the ST900ELV has proved to be
highly successful
Growth in demand has been
outstanding
Growth of ELV systems
(% of UK intersection controllers shipped as ELV)
Actual
75%
Forecast
 Forecast to continue
But with no dedicated ELV
Pedestrian Controller available,
Traffic Managers have struggled to
follow an ‘ELV only’ installation
policy
50%
25%
(Excl TfL)
06/07
07/08
08/09
09/10
Financial Year
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Challenges creating an ELV pedestrian controller
Price pressure in the stand-alone
pedestrian market
 Must be cost effective but still offer
the full range of ELV benefits
 Both product and development
costs must be considered
Maintaining support for both LV and
ELV solutions
Effect of development costs
Example: Assume sales of 500 ELV pedestrian controllers per year:
(Development costs to be recovered in three years)
Example 1
Example 2
Development cost:
£900K
£300K
Recovery per year:
£300K
£100K
Additional cost per controller:
£600
£200
Ensuring product reliability is not
compromised by need to minimise
costs
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The Siemens solution – The ST750 family
Offers LV/ELV mix (as per ST700)
and also a complete ELV solution
In common with the ST900, the
ST750 family is provided in two
distinct TR2500 compliant types
 ST750
 ST750 ELV
ST750 is based on the ST700
ST750 ELV uses the latest ELV
technology employed in the
ST900 ELV
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The ST750 ELV
The benefits of the Siemens ST900
ELV traffic system
 Built in lamp monitoring including
nearside and LED wait indicators
 ‘DC’ drive with advanced switching
supporting extended cable runs
 Support for very low power signals
 Electronic protection of all outputs
to minimise damage in the event
of cable faults
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New cabinet layout, building on the
success of the ST900ELV
 Both small and large sizes
available
Offers all the same benefits as the
ST900ELV
Retains familiar IC4 configuration
tool
 Newly upgraded to include many
new emulation features
You can see the ST750 ELV
controller and the new IC4 system
on the Siemens stand C10
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ELV – The total solution?
ELV can now be total solution for new
installations
 Will deliver greater safety, lower installation
costs and reduced carbon footprint
But there are thousands of sites installed using
LV incandescent signals
 Much of this installed equipment is still
serviceable
 The cost of mass upgrade may be difficult to
justify
The benefits of lower running costs and reduced
carbon footprint can still be achieved with the
new Siemens Helios retrofit solution
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Standard Siemens LED signal
Helios CLS with Lamp Monitoring
Facility (LMF)
Helios CLS with LMF
Benefits:
 Robust Helios signal body
 SIRA high phantom lens
 Lamp monitoring compatibility with
all Siemens controllers
 Reduced power compared with
standard high intensity signals
LMF Module
CLS Module
Disadvantages
 Integral LMF adds cost
 LMF raises power consumption
above basic LED levels
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The Siemens retrofit
Objectives
Eliminate the need for the LMF unit
 Reduces cost
 Reduces power consumption
Provide effective retrofit kits for
existing Helios signals
 LV and ELV options
(Option for Peek Elite being
considered)
Be fully compatible with ST800 and
ST900 intersection controllers
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The Siemens retrofit - Benefits
Impact on controllers:
Helios CLS (retrofit)
 New lamp switch cards
 New firmware
Benefits:
 Able to be added to existing
controllers without re-configuration
 Retains all benefits of the existing
Helios traffic signals
 Protects investment in installed
infrastructure
 Fully RLM compatible and meets
the timing requirements of TR2210
and TR2500
 Reduced power compared with HI
signals and standard Helios CLS
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LMF Module no
longer needed
Updated
CLS Module
Retrofit modules supplied
complete with new door, lens
and hoods
• Minimises installation time
• Ensures best possible
optical performance
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The Siemens retrofit – potential power savings
Indicative power consumptions
Helios CLS
(with LMF)
Helios ELV
Helios CLS
Retrofit (2)
Average power
21W
8W
9W
Saving v High Intensity signals
50%
80%
78%
Typical Junctions annual power saving – compared with High Intensity signals
Large site – 30 x 3 aspect heads, 6 x single aspect arrows
Medium site – 14 x 3 aspect heads, 4 x single aspect arrows
Small site – 7x 3 aspect heads, 2 x single aspect arrows
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4 Phase
8 Phase
Estimated annual power saving
2163 KWh
4328 KWh
9093 KWh
Approximate annual carbon saving
1.2 Tonnes
2.4 Tonnes
4.9 Tonnes
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12 Phase
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Summary
ELV is the ideal solution for new
installations
For existing sites, significant
carbon savings can be achieved
by upgrading to LED signals
using the Helios retrofit option
Together these two solutions offer
real opportunities for significant
power and carbon savings
Questions…….
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ELV – The total solution?
Copyright © Siemens plc 2009. All rights reserved.