Mitsubishi S4S Service Manual page 48

ADJUSTMENTS, BENCH TEST, PERFORMANCE TESTS
(5) Deterrnining speed regulation (speed droop)
[I] Speed regulation upon removing load
(a) Run the engine with the speed control lever
set at the position for the rated load and speed.
(b) Vnder this condition, remove the load to bring
the engine into no-load condition. Do not
move the speed contral lever.
(c) The engine speed will increase once and
decrease and settle at a new steady state level
as shown. Read the highest speed (N2)
occurring in this transition and the speed (N3)
after settling, and the time
(tr)
from the
moment of removing the load at the initial
speedtbli) to the settling at the new level (N3).
[2] Speed regulation upon applying load
With the engine running under no-load condition
subsequentto the condition mentioned in (b), [1],
above, and with the speed control lever held in
the same position as above, apply the prescribed
load instantaneously to the engine: the engine
speed will decrease once and increase, as shown,
and settle at a new steady state level. Read the
lowest speed (Ns) occurring in this transition and
the speed (N6) af ter settling, and the time
(ts)
from
N4 to N6.
[3] Calculate the speed regulation
From the values obtained in [1] and [2], above,
compute the speed regulation for each load
change. A total of four percent values of speed
regulation are to be determined by using the
indicated forrnulas.
If the computer values are at varianee with the
prescribed values, "governor notch adjustment"
should be made to eliminate the varianee.
5-8
Speed regulation upon removing load
N,
Instantaneous speed Steady-state speed
regulation
(%)
regulation
(%)
Nz-
NI N3-NI
NI
X
100
NI
X
100
NI
=
initial speed, min-I, before load is
removed
N, = highest speed, min-I, during transitional
period
N3
=
speed, min-I, at which the engine settles
after load is removed
ti
=
stabilization time
Speed
regUlatiO~n
upqn,applying load
N.
N,
Instantaneous speed Steady-state speed
regulation
(%)
regulation
(%)
N4- Ns
N4-N6
N4
X
100
N4
X
100
N4 = initial speed, min-I, before load is
applied
Ns
= lowest speed, min-I, during transitional
period
N6
=
speed, min-I, at which the engine settles
after load is applied
tz
=
stabilization time