Teledyne 440, System Manual, Page: 57 / 256

4 – Electrical Installation
DPN 402196 Issue 4.1 © Teledyne TSS 4- 11
4.2.2.1 Alternative Communication Methods
WARNING
There is a risk of death or serious injury by electric shock when you work inside
the SDC, the SEP or the PSU. Only a competent engineer who has the relevant
training and experience should open any part of the 440 System. Power-off and
isolate the equipment from the mains supply voltage before you open any part of
the 440 System. Observe all relevant local and national safety regulations while
you perform any maintenance work on the 440 System.
Re-fit all safety covers and ground connections to the 440 System before you re-
connect the equipment to the mains electrical supply.
Many components within the SDC are susceptible to damage due to electrostatic
discharge. You must take precautions against such damage. These precautions
include the use of a grounded conductive mat and wrist-strap. Teledyne TSS will
not accept responsibility for any damage caused by failure to take such
precautionary measures.
NOTE
The following instructions are valid for the SDC Type 10 shipped as part of the 440
System. If required, contact Teledyne TSS for advice for instructions relating to
older versions of the SDC.
The standard communication link between the SDC and the sub-sea installations of the 440 System
uses RS232 communications. This method of communication is only suitable for use with umbilical
cables up to 15m. To configure the 440 System to use an alternative communication method, you must
change link settings inside the SEP and the position of the external switch on the SDC comms
enclosure.
The alternative communication methods are:
❐
4-wire 20mA digital current-loop
Suitable for use with umbilical cables longer than 1000 metres, or where the quality of the umbilical
cable prevents effective use of the standard 2-wire method.
In practice, the 4-wire method should be suitable for use with umbilical cables up to 4000 metres
long if the umbilical is of good quality.
❐
2-wire 20mA digital current-loop
If the umbilical cable is of good quality, experience has shown that you may use this
communication method successfully through transmission distances up to 1000 metres.
Configure the SEP
CAUTION
Many components inside the SEP are susceptible to damage due to electrostatic
discharge. You must take precautions to prevent such damage whenever you
open the SEP. These precautions include the use of a grounded conductive mat