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4
EA42-7
● The voltage regulator is shipped from the factory
with a link across terminals P and Q. If a remote
voltage adjust rheostat is used, the link should be
removed and the Rheostat connected to P and Q.
A 1 ohm, 1W. P
otentiometer will provide a “fine”
voltage range adjustment of approximately
10%
over most of the coarse range of adjustment.
See Figure 4 interconnection diagram.
2.7
V/Hz “Corner Frequency” Selection
For 50 Hz systems, the regulator is pre-set at the
factory for a 45
Hz “ corner frequency ”, and a link
fitted across ter
minals “50”. If operation at 60 Hz is
required, this link should be removed; the “ corner
frequency ” is now set to 55 Hz. Do not operate the
system at 60 Hz with the 50 Hz link still in place.
2.8 Over-Excitation Shutdown
● Over-excitation shutdown is provided to remove
output excitation should the regulator’s output
voltage exceeds 52
2 Vdc for a sufficient time.
The inverse-time delay curve is shown in Figure
1-2. For voltage above 95
5 Vdc, there is a
second and much shorter inverse time curve.
● After output power is removed, the regulator can
be reset by decreasing the input voltage to less
than 5 Vac for a minimum of 2 seconds; this may
be .accomplished by stopping the prime mover or
interrupting the regulator input by means of a
reset switch.
● In cases where the generator is operating in a
parallel mode, it is sometimes considered
undesirable to allow the regulator to shut down,
which may cause the generator to be “ motored”.
The regulator is provided with terminals N and D,
which may be linked together to prevent
over-excitation shutdown. Note however that
continuous running at output levels greater than
the continuous rating may result in eventual
regulator failure, and that other means should be
employed to protect the system.
3. OPERATION PROCEDURE
3.1 General
● The following system operation procedures
provide instructions for adjusting the EA42-7
voltage regulator. Symptoms resulting form a
faulty regulator and certain generator system
problems are included, together with suggested
remedies.
● Complete the following steps before proceeding
with system start-up.
CAUTION !
Meggers and high-potential test equipment must not
be used. Incorrect use of such equipment could
damage the semiconductors used in the regulator.
3.2 Preliminary Set-Up
● Verity that the voltage regulator specifications
conform with the generator system requirements.
● Ensure that the regulator links are fitted correctly
where required, as follows:
1. If the remote voltage adjust rheostat is not
required, ensure terminals P and Q are linked
together.
2. If a 55 Hz corner frequency for 60 Hz systems
desired, ensure the “ 50~50 ” link is removed. If a
45 Hz corner frequency for 50 Hz systems is
desired, ensure the “ 50~50 ” link is connected.
3. If the system is to be run in parallel, consider
whether shutdown of the generator’s excitation is
acceptable. If not, ensure that the link between
terminals N and D is in place.
● Ensure the voltage regulator is correctly
connected to the generator system; F+ to field
positive, F- to field negative, and terminals 3 and
4 to the auxiliary winding supply. It is vital that the
sensing connections are correctly made to all 4
wires U, V, X, and Y. Ensure the metal ring tag at
one mounting hole is bonded to ground via either
a metal screw or shout length of cable.
● Install the fuses as per paragraph 2-5.
● Set the regulator and external voltage adjust, if
used, as follows :
Regulator Vo
lts Adjust “ V ” Fully CCW
Remote Volts Adjust
Centered
Stability Adjust “ S ”
Centered
3.3 System Start-Up
● Perform preliminary set-up, per paragraph 3.2,
checking wiring carefully.
NOTE :
All AC voltage readings are to be taken with an
“ average ” reading voltmeter.
● Start Prime-mover and bring up to rated speed.
RESULT :
Voltage should build up to less than nominal value. If
not, proceed to paragraph 3.4.
