GE Industrial Solutions MX350 Instruction manual - Manual (Page 92)

5–18 MX350 AUTOMATIC TRANSFER CONTROL SYSTEM – INSTRUCTION MANUAL
CONTROL CHAPTER 5: SETPOINTS
Once this feature is enabled, the user can assign one of the configurable outputs to be
turned on when the Auto Load Shed logic in the controller senses a condition that warrants
a load shed. This is done on the setpoints > config > outputs > alarms screen. The user
can then wire this output to trip a downstream breaker.
In the example above, the Auto Load Shed output will be triggered when the frequency
falls below 59.0Hz for more than 3 seconds, when the voltage drops to less than 95% of
nominal, or when the power of the switch increases to 103% of nominal. If this output is
used to trip a downstream load breaker, a part of the load fed by the switch can be shed in
order to stabilize the generator and keep the system from failing due to overload.
If desired, the user can also bypass the load shedding due to a KW overload condition. To
do so, the ‘Auto Load Shed KW Bypass’ parameter on the Control screen needs to be
changed from ‘Disabled’ to ‘Enabled’.
The output will remain energized until the user manually clears the Load Shed on the
Status screen of the controller.
If the ATS has been ordered with the R15 option, the user will be presented with the Auto
Load Shed Mode selector on the Control screen. If the mode is set to ‘Remote’, the logic of
the controller will trip a downstream breaker as indicated above. If, however, the mode is
set to ‘Local’, the whole switch will disconnect from the S2 power source and the complete
switch load will be without power.
Auto Load Shed Mode, Auto Load Shed KW Bypass, and Auto Load Shed Reset can also be
controlled by hardwired or communicated inputs.
NOTE
NOTE: If either the hardwired user configurable input or the selector on the control switch has
been set to ‘Local’, the ATS will disconnect from the S2 power source when the controller
detects a Auto Load Shed condition. In order to have the Auto Load Shed trip a
downstream breaker, the mode selector on the Control screen has to be set to ‘Remote’
and the hardwired input (if configured by user) has to be OFF.
NOTE
NOTE: Great care has to be used by the customer to properly apply the Auto Load Shed feature in
order to avoid unintentional power loss to the switch load.
Sync phase angle limit
NOTE
NOTE: This is applicable only to Closed Transition type switches.
With this variable, the user can select the allowable phase angle difference between
Source 1 and Source 2 for Closed Transition transfer. The default is 10°.
Interlock