The import/export control is an integrating control. It adjusts the percentage of

rated load carried by the individual generators, operating in isochronous load

sharing, in order to maintain a set import/export or base load level. The MSLC

will therefore maintain a constant base load or import/export level even with

changing utility frequencies. The MSLC provides switch inputs to allow raising or

lowering the internal digital base load or import/export reference. The control also

provides a 4–20 mA (1–5 Vdc) analog input for remote reference setting, if desired.

The MSLC is equipped with a Utility Unload switch, which provides an adjustable

time controlled ramp to lower the base load or import/export level. When the level

is below an adjustable threshold, the MSLC issues a breaker open command to

separate the utility from the local bus. Again, the ramp pause switch can be used

to stop the utility unload at any point.