Woodward MSLC Master Synchronizer and Load Control Discrete Inputs

Discrete Inputs

The discrete inputs are the switch input commands to the MSLC. Discrete inputs

are optically isolated from the control and require 10 mA at 24 Vdc each to

activate. Discrete inputs may be powered by the same source as control power.

All contacts used in the discrete circuits should be the isolated dry contact type to

work properly with the low currents used in these circuits.

Connect the 24 Vdc supply common (–) to terminal 43. Route +24 Vdc through

the appropriate external contact to the discrete input.

Synchronizer Mode Switch

The synchronizer mode switch (single-pole, four-position) controls the operating

mode of the synchronizer. The switch must be wired to terminals 44. 45. and 46.

as shown in Figure 1-3. The four positions are Off, Check mode, Permissive

mode, and Run mode. When the switch is off, the synchronizer is out of operation.

CB Aux Contact

Connect the utility breaker auxiliary (CB Aux) contact that opens and closes

when the utility tie breaker opens and closes. Wire the breaker auxiliary contact

in series between the +24 Vdc voltage source and terminal 47 of the MSLC. In

addition, it may be desirable to put an MSLC ON/OFF switch in series with this input.

Utility Unload Contact

Connect the utility unload switch to terminal 48.

Import/Export Control Contacts

The import/export mode of control is initiated by closing the CB Aux contact 47

and closing the import/export contact 49.

Process Control Mode Contact

If the MSLC will be used as a process control, connect a switch from +24 Vdc to

the Process Control discrete input, terminal 50. When this contact is closed, load

on the associated DSLC™ equipped generators in isochronous load sharing is

controlled at a level required to maintain the analog process input at a chosen reference.

Ramp Pause Contact

Connect the load ramp pause switch contact to terminal 51. When closed, this

contact will hold any load ramp in progress at its current setting until the contact is opened.

Raise and Lower Set Point Contacts

Connect a center off, double-pole double-throw switch to the Raise and Lower

Load inputs, terminals 52 and 53. If the remote reference will be used, install a

second double-pole double-throw switch to simultaneously select both the Raise and Lower inputs.

Local Bus Voltage Adjustment Contacts

The Local Bus voltage adjustment contact inputs allow manual voltage control of

the operating generator's voltages for manual paralleling. Note, if the individual

generators are in VAR/PF control, they will return to VAR/PF control as soon as

the MSLC's raise/lower switches are returned to OFF. The switches may also be

used to change the constant generator power factor reference if operating in that mode.