Earth Leakage Circuit Breaker (Elcb); Instruments And Controls; Armature; Bearings - Ingersoll-Rand P90 Operation And Maintenance Manual With Parts Catalogue

37
OPTIONS
De–rating factor:
Air in temp 40 C
Air in temp 50 C
Air in temp 60 C
Socket outlets:
P130 110 volts
option
or 220 volts
The generator is a two pole, rotating armature, slip ring machine and
is belt driven from the engine. It produces 50Hz (single phase)
alternating current (a.c.) voltage when driven at a constant 3000
revolutions per minute.
The armature has two separate windings connected in series. The
series connection being brought out to the earth slipring (furthest from
bearing).
The 110 volt armature has two 55 volt windings and the 220 volt
armature has two 110 volt windings. Therefore it is not practicable to
change output voltage in the Field.
The field windings consist of two coils connected in series, one coil
is mounted on each pole piece.
The no–load excitation current is taken from the armature via a
series capacitor and a rectifier bridge. The value of the capacitor is
chosen to give the correct field current for nominal volts (110volts or
220 volts) under no–load conditions. The value of the capacitor(s) may
vary from one alternator to another.
The on–load excitation current is supplied by a current transformer,
the primary of which is in series with the alternator output.
The ratio of the current transformer is such that the correct field
current is maintained under all load conditions.
The windings are insulated to class F throughout maximum
temperature 155 C.
Miniature circuit breakers (MCB) are fitted to provide both
overcurrent and short circuit protection for the generator.
Earth leakage protection is provided by a single residual current
device rated at 63 amperes with 30 milliamperes tripping sensitivity.
Each socket outlet is protected by a spring loaded weather-proof
cover.
OPERATING INSTRUCTIONS
A mode selector switch is provided to switch the machine between
compressor and generator mode.
CAUTION: Do not start or stop the machine with the
compressor/generator mode switch in the Generator position.
When the switch is in the Generator position the normally–open
solenoid valve switches to the closed position and air in the line to the
engine speed control cylinder vents to the atmosphere via the solenoid
exhaust port. This causes the cylinder to move to its maximum speed
position. The engine will now maintain maximum speed as the air line
from the pressure regulator valve to the solenoid valve is now closed.
When the switch is returned to the Compressor position, the
solenoid valve is de–energised thus returning it to its normally open
position. The engine speed cylinder would then respond via the
pressure regulator valve according to the air demand.
P90 P101 P110 P130
HP95 P150 P180 HP140
Continuous
–1
45 min. h
–1
30 min. h
2 x 16 amperes
1 x 32 amperes
1 x 5 amperes
2 x 16 amperes
When connecting electrical equipment to any of the socket outlets,
it is recommended that the appropriate MCB is in the OFF position
before making the connection, switching the MCB to the ON position
immediately prior to using the equipment.
MAINTENANCE
General
Ensure all electrical equipment is properly maintained and
controlled.
Ensure all earth connections are secure and regularly maintained.

Earth leakage circuit breaker (ELCB)

The earth leakage circuit breaker must be mechanically tested daily
by pushing the test button with the machine in its no load condition. The
ELCB should trip to the off (down) position.
The earth leakage circuit breaker should also be tested every 3
months. A proprietary test meter should be used to induce live to earth
preset flow at each socket outlet. This current flow will produce the
required earth fault check. The test should be conducted in accordance
with appropriate national standards.

Instruments and controls

A Voltmeter is provided to indicate the output voltage. On No–load
it will show a nominal 110 or 230 volts. In practice this may be factory
set to a maximum 120 or 240 volts repectively. On Full Load the
readings may reduce to 103 or 206 volts.
On 110 volt machines a socket selector switch is provided to select
either the two 16 ampere sockets or the single 32 ampere socket.
Miniature circuit breakers provide over–current protection. In the
event of currents in excess of 16 amperes or 32 amperes (110 volt
machine only) from the sockets, the appropriate circuit breaker will trip
to the OFF position.
Note: The current trip rating is quoted at a nominal 40 C ambient
temperature.
An earth leakage circuit breaker provides additional protection in
the event of a leakage to earth in excess of 30 milliamperes on the
connected appliance or in the connections to the generator.

Armature

To check the armature proceed as follows:
Remove the field leads from the rectifier, the marked lead being the
positive, and connect them to a 12 volt battery.
Start the machine and measure the voltage across the sliprings.
The voltage between sliprings 1 and 3 should be the same as the
voltage between sliprings 2 and 3 (slipring 1 being nearest the bearing).
If the voltages vary significantly then suspect the armature windings.

Bearings

The generator bearings are sealed for life and require no
maintenance.
Brushes
Inspect the brushes periodically for wear and replace if required.