ABB Distribution Protection Unit 1500R
1-28
Protective Functions
9/99
website:www.abb.com/papd
Alternate Settings Groups
The DPU1500R has three separate and identical selectable settings groups for protective relay functions. These
groups are labeled Primary, Alternate 1 and Alternate 2. Use of the three groups provides flexibility to quickly change
parameters according to some external conditions. For example, Alternate 1 settings might be used during a High load
time while Alternate 2 settings might be used when a storm is pending (and modified instantaneous settings are
desired). Other uses might be winter/summer settings or line maintenance settings.
In order to activate these alternate settings groups remotely, the logical inputs ALT1 and ALT2 assigned (in the
programmable inputs screen of the Windows External Communications Program - WinECP) to programmable input
contacts such as IN1 and IN2 respectively. Once the logic functions are assigned, to IN1 and IN2, they can be wired
to electronically controlled switches which can be actuated through SCADA. (Note: The programmable input contacts
can also be actuated through one of our various protocol options by simply issuing the proper commands).
The internal logic of DPU1500R will only allow one settings group to be active at a time. When ALT2 is active and an
ALT1 input is asserted, ALT2 stays active until the ALT2 input is de-asserted. Only then will the ALT1 settings group
become active. Note: there is a 2 cycle time delay that occurs between the settings group change. Protection is never
disabled during these changes.
As an example, assign the ALT1 logic function to programmable input IN1 with enabled when closed logic and the ALT2
logic function to programmable input IN2 with enabled when closed logic. Externally wire IN1 to a control switch to be
used for Cold Load control and wire IN2 to a control switch to be used for storm settings. If the Cold Load settings (IN1)
must have priority over primary settings as well as storm settings (IN2), assign the ALT2 logic function also to
programmable input IN1 with enabled when open logic (see Figure 1-16). The logic will force ALT2 to be disabled
whenever ALT1 is enabled.
All of the protective elements outlined in the “Protective Elements” Section are available in the Primary, Alternate 1,
and Alternate 2 settings groups. All other settings in the relay such as the Configuration settings, Programmable
Inputs, Programmable Outputs, etc. are fixed at one group and follow the three protective settings groups. These other
settings typically do not change once the relay is set and commissioned.
Figure 1-16. Sample Alternate Settings Programmable Input Logic Assignments