13
5.4 PROTECTION
Although the AVR incorporates certain protective elements
as already described, it is the responsibility of the end user
and his contractors/sub-contractors to ensure that the overall
system protection meets the needs of any inspectorate, local
electricity authority or safety rules, pertaining to the site
location.
High voltage transient surges generated by a switching
device or lightning strikes on overhead cables must be
prevented from reaching the generator terminals by the
fitting of correctly designed surge suppression devices.
These must be connected as close to the generator
terminals as practicable, and ideally consist of surge
arresters and surge capacitors.
A separate Newage publication, entitled Applications
Guidelines, covers this topic more fully and is available upon
request.
Where generators are connected to overhead transmission
lines either directly or via transformers, the overhead lines
should be fitted with surge arresters to reduce surge levels
on the more immediate generator protection. Overhead line
arresters should ideally be at a distance of 350m from the
generator.
To enable the system designer to achieve the necessary
protection and/or discrimination, fault current curves are
available on request from the factory, together with generator
reactance values to enable fault current calculations to be
made.
On LV generators the star point busbars arrangement allows
for the fitting of differential protection current transformers.
Provision has been made for an earth leakage detection
current transformer which is positioned between the star
point and neutral terminal.
On MV and HV generators the main stator winding has six
leads brought out to terminals in the terminal box. The three
leads brought to the neutral terminal have been arranged to
allow for the provision of differential protection with the
option of clamps and mounting plates for specific current
transformers supplied by Newage International.
If it becomes necessary for customers to use current
transformers not of Newage supply, these should be fitted in
an engineered manner with particular care being taken to
ensure the cables are positioned centrally within the current
transformer opening.
Generator output terminals can be offered in an arrangement
to suit the fitting of specific DIFFERENTIAL PROTECTION
current transformers supplied by Newage International. This
requirement should be specified at time of order.
Warning!
Incorrect installation and/or protective
Systems can result in personal injury
and/or equipment damage.
Installers must be qualified to perform
electrical installation work.
5.5 COMMISSIONING
Ensure that all external cabling is correct and that all the
generating set manufacturer's pre-running checks have been
carried out before starting the set.
The generator AVR controls will have been adjusted during
the generating set manufacturer's tests and should normally
not require further adjustment.
Should malfunction occur during commissioning refer to
Service and Maintenance section 'Fault Finding' procedure.
