ST750
G
ENERAL
H
ANDBOOK
667/HB/33750/000
Page 16
Issue 6
2. SPECIFICATION
The Specification that follows is for the ST750 Cabinet Assembly. Where
appropriate it also applies to the ST750 Rack Assembly as supplied for installation
in another Cabinet.
Non-UK specifications are detailed where they differ from standard UK
specifications.
2.1 Equipment Introduction
The ST750 is a Pedestrian Controller and Small Non-UK Traffic Controller and can
be supplied in either small or large single-door outer cases.
It can be supplied as
•
Single Pedestrian controller (2 Phase)
•
Dual Pedestrian Controller (4 Phase)
•
Small Non-UK Controller (6 Phase)
Generally it comes as a fully fitted Cabinet Assembly with its own equipment,
mounting stool, mains distribution, power supplies, electronic control and phase
switching
This ST750 Cabinet Assembly can also accommodate Detectors, I/O PCB, OTU
PCB, an OMU Assembly, Manual Panel, Master Switch Assembly and a Dimming
Transformer.
It may also be fitted as a “Cuckoo” into many existing cabinets, when supplied as a
Rack Assembly consisting of the power/phase assembly and a CPU. There are a
number of conversion kits available that enable it to be installed into other cabinets.
The ST75
0’s electronics consist of three PCBs:
•
The CPU PCB that contains most of the logic, which controls the system and the
extra low voltage inputs and outputs, i.e. detector inputs, audible outputs, etc.
•
The Phase Drive PCB that contains most of the Mains distributions, the triac
phase drive outputs, voltage and current monitoring.
•
The PSU (24V) that provides the main power supply for the ST750.
The CPU PCB operates under the control of both a main and a secondary
processor. The main processor is a Motorola 68340, which runs the firmware
controlling all the functions of the ST75
0’s operations. The secondary processor is
an Intel 80C31 controlling all the phase output switching and voltage monitoring.
The two processors communicate with each other through shared RAM. This dual
