About the 9905-798
This model is part number 9905-798, a microprocessor-based Digital Synchronizer and Load Control manufactured by Woodward. This model is designed to be used in the paralleling, synchronizing, loading, and unloading of three-phase AC generator sets. 9905-798 does not have power factor control or process control functions, as it is one of the reduced upgrade level models in this Woodward series.
Woodward's 9905-798 Model has a WYE PT Configuration. It is rated for use in operating temps from –40 to +70 °C (-40 to 158 F) and storage temps from –55 to +105 °C (-67 to 221 F). Additional environmental specifications for the 9905-798 are:
- Humidity …... 95% at 38 °C
- Mechanical shock …... US MIL-STD 810C, Method 516.2, Procedures I, II, V
- Electromagnetic susceptibility …... ANSI/IEEE C37.90.2; ANSI C37.90.1-1989
- Vibration …... US MIL-STD 167, Type I
Built-in diagnostics; automatic generator loading and unloading; setup, metering, and diagnostic capability through a handheld programmer terminal; droop, baseload, and isochronous load control capability; and reverse power relay are just a few of the available functions.
A few of the load control features of the 9905-798 DSLC include:
- A frequency trimmer function for accurate frequency control in isochronous load sharing systems
- Simple load droop operation provides safe operation in parallel bus applications
- Adjustable load switch output with independent pick-up and drop-out points
- Load raise and lower inputs to adjust speed before synchronizing
- Voltage raise and lower inputs to adjust voltage before synchronizing
The 9905-798 offers either phase matching or slip frequency synchronizing. Actual slip frequency and breaker delay values are used to anticipate a minimum phase difference between generator and bus at actual breaker closure for both methods. There is an automatic dead-bus closure function on this control, where only one DSLC control is granted dead-bus closing permission through locking techniques over the communications network.
Additional synchronizer features include:
- Time-delayed automatic multi-shot reclosing
- Voltage matching
- Auto-resynchronizing
- Synchronizer timeout alarm
These features may be enabled or disabled during setup.
