PI Manufacturing AC generators - Manual (Page 8)

SECTION 3
APPLICATION OF THE GENERATOR
The generator is supplied as a component part for installation
in a generating set. It is not, therefore, practicable to fit all the
necessary warning/hazard labels during generator
manufacture. The additional labels required are packaged
with this Manual, together with a drawing identifying their
locations. (See below).
It is the responsibility of the generating set manufacturer to
ensure that the correct labels are fitted, and are clearly visible.
The generators have been designed for use in a maximum
ambient temperature of 40°C and altitude less than 1000m
above sea level in accordance with BS5000.
Ambients in excess of 40°C and altitudes above 1000m can
be tolerated with reduced ratings - refer to the generator
nameplate for rating and ambient. In the event that the
generator is required to operate in an ambient in excess of the
nameplate value or at altitudes in excess of 1000 metres
above sea level, refer to the factory. The generators are of air-ventilated screen protected drip-
proof design and are not suitable for mounting outdoors
unless adequately protected by the use of canopies. Anti-
condensation heaters are recommended during storage and
for standby duty to ensure winding insulation is maintained in
good condition.
When installed in a closed canopy it must be ensured that the
ambient temperature of the cooling air to the generator does
not exceed that for which the generator has been rated.
The canopy should be designed such that the engine air
intake to the canopy is separated from the generator intake,
particularly where the radiator cooling fan is required to draw
air into the canopy. In addition the generator air intake to the
canopy should be designed such that the ingress of moisture
is prohibited, preferably by use of a 2 stage filter.
The air intake/outlet must be suitable for the air flow given in
the following table with additional pressure drops less than or
equal to those given below :
Air Flow
Frame
50Hz 60Hz
Additional
(intake/outlet)
Pressure Drop
0.216m³/sec 0.281m³/sec 6mm water gauge
UC22
458cfm 595cfm (0.25”)
0.25m³/sec 0.31m³/sec 6mm water gauge
UCD22
530cfm 657cfm (0.25”)
0.514m³/sec 0.617m³/sec 6mm water gauge
UC27
1090cfm 1308cfm (0.25”)
0.58m³/sec 0.69m³/sec 6mm water gauge
UCD27
1230cfm 1463cfm (0.25”)
Important ! Reduction in cooling air flow or inadequate
protection to the generator can result in
damage and/or failure of windings.
Dynamic balancing of the generator rotor assembly has been
carried out during manufacture in accordance with BS 6861
Part 1 Grade 2.5 to ensure vibration limits of the generator are
in accordance with BS 4999 Part 142.
The main vibration frequencies produced by the component
generator are as follows:- :
4 pole
1500 rpm 25 Hz
1800 rpm 30 Hz
However, vibrations induced by the engine are complex and
contain frequencies of 1.5, 3, 5 or more times the fundamental
frequency of vibration. These induced vibrations can result in
generator vibration levels higher than those derived from the
generator itself. It is the responsibility of the generating set
designer to ensure that the alignment and stiffness of the
bedplate and mountings are such that the vibration limits of
BS5000 Part 3 are not exceeded.