4-14 DECS-100 Installation 9287500991 Rev K
4. Connect only the DECS-100 power input terminals to an auxiliary power source. Before applying
DECS-100 operating power, observe the precautions noted in Operating Power Considerations
During DECS-100 Programming.
5. Perform all initial DECS-100 settings by connecting a PC operating with BESTCOMS to the rear
communication port of the DECS-100 and save all new settings.
6. Remove power from the DECS-100.
7. Connect the rest of the DECS-100 leads using the tagged identification.
8. Start the prime mover/generator and perform the final adjustments at rated speed and load.
9. After the initial startup, the DECS-100 should not require any further adjustments unless there is a
change in the system.
Operating Power Considerations During DECS-100 Programming
Due to its pulse-width modulated (PWM) power stage, the DECS-100 operating power input has a
substantial amount of capacitance. High inrush current can be experienced upon DECS-100 power-up
when a "solid" power source is used. When powering the DECS-100 for programming with voltage
greater than 120 Vac, high inrush current may damage the unit. Therefore, during programming, DECS-
100 operating power should be within the range of 30 to 120 Vac (50/60 Hz).
If it is necessary to perform programming with applied operating power over 120 Vac, a current-limiting
resistor must be connected between the power source and DECS-100 (Figure 4-12). A resistor rated at
20 ohms and 20 watts may be used to limit the inrush current to a safe level. During the duration of the
inrush current (about one cycle), the resistor power rating will be exceeded. Once the inrush has passed,
the resistor power dissipation level will be minimal. If desired, a 10 ohm, 50 watt resistor may be used
instead.
Figure 4-12. Operating Power Connections for DECS-100 Programming (Input Voltage >120 Vac)
These special operating considerations are to be observed only during DECS-100 programming.
Applications where the DECS-100 is powered from the generator output (shunt powered) or a permanent
magnet generator (PMG) are still valid within the constraints given in Section 1, General Information,
Specifications. In applications where station power is used to power the DECS-100, the DECS-100
should be protected by an Inrush Current Reduction Module (ICRM-7). See
Power Supply Inputs
for more
information.
ADJUSTMENTS
All adjustments are made using external switching, or with BESTCOMS software via the rear panel
communication port. See Sections 5 and 6 for more information regarding setting adjustments with
BESTCOMS software.
When programming the DECS-100 without the generator spinning, the
connections to DECS-100 terminals F+ and F– should be removed.
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