DSE Model 8620 AMF Controller Operators Manual
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Factory settings for the IDMT Alarm when used on a brushless alternator are as follows (screen
capture from the DSE Configuration Suite PC software :
These settings provide for normal running of the generator up to 100% full load. If full load is
surpassed, the Immediate Warning alarm is triggered, the set continues to run.
The effect of an overload on the generator is that the alternator windings begin to overheat; the aim of
the IDMT alarm is to prevent the windings being overload (heated) too much. The amount of time that
the set can be safely overloaded is governed by how high the overload condition is.
With typical settings as above, the tripping curve is followed as shown below.
This allows for overload of the set to the limits of the Typical Brushless Alternator whereby 110%
overload is permitted for 1 hour.
If the set load reduces, the controller then follows a cooling curve. This means that a second overload
condition may trip much sooner than the first as the controller knows if the windings have not cooled
sufficiently.
For further details on the Thermal damage curve of your alternator, you are referred to your alternator
manufacturer and generator supplier.
I
T
(Trip setting
value)
t
(time multiplier)
