Marathon Computer AACC 2000 - Manual (Page 5)

Marathon Monitors Inc.
AACC 2000 Carbon Nov. 1, 1997
5
Installation Safety Requirements
Safety Symbols
Various symbols are used on the instrument, they have the following meaning:
Caution, (refer to the
accompanying documents) Functional earth
(ground) terminal
!
The functional earth connection is not required for safety purposes but to ground RFI filters.
Personnel
Installation must only be carried out by qualified personnel.
Enclosure of live parts
To prevent hands or metal tools touching parts that may be electrically live, the controller
must be installed in an enclosure.
Caution: Live sensors
The fixed digital inputs, non-isolated dc, logic and outputs and the logic output of dual
output modules, are all electrically connected to the main process variable input. If the
temperature sensor is connected directly to an electrical heating element then these non-
isolated inputs and outputs will also be live. The controller is designed to operate under
these conditions. However you must ensure that this will not damage other equipment
connected to these inputs and outputs and that service personnel do not touch connections to
these i/o while they are live. With a live sensor, all cables, connectors and switches for
connecting the sensor and non-isolated inputs and outputs must be mains rated.
Wiring
It is important to connect the controller in accordance with the wiring data given in this
handbook. Take particular care not to connect AC supplies to the low voltage sensor input
or other low level inputs and outputs. Only use copper conductors for connections (except
thermocouple inputs) and ensure that the wiring of installations comply with all local wiring
regulations. For example in the in the UK use the latest version of the IEE wiring
regulations, (BS7671). In the USA use NEC Class 1 wiring methods.
Power Isolation
The installation must include a power isolating switch or circuit breaker. This device
should be in close proximity to the controller, within easy reach of the operator and marked
as the disconnecting device for the instrument.
Earth leakage current
Due to RFI Filtering there is an earth leakage current of less than 0.5mA. This may affect
the design of an installation of multiple controllers protected by Residual Current Device,
(RCD) or Ground Fault Detector, (GFD) type circuit breakers.