Manual 37942A DTSC-200A - ATS Controller - Application
© Woodward Page 9/21
Special Applications
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Example Application: Transfer Delay (Util-Util)
The example shows two DTSC-200A (ATS 1 & ATS 2) which are feeding two loads (Load 1 & Load 2). Since
the two mains sources are always present, all stable delay timers are always expired. In case “Source 1” would
fail, both ATS would transfer both loads to “Source 2” immediately. In some transfer scenarios the loads can
have different priorities. In a hospital for example, “Load 1” could be the “Emergency” load and “Load 2” a
“Non-Emergency” load. In that case the system owner wants the “Emergency” loads to be transferred first, and
“Non-Emergency” loads to be transferred second. In such a scenario the “Transfer delay timers” become an im-
portant tool to prioritize the loads. See the following example:
Figure 2-4: Example application - transfer delay (Util-Util)
Example details:
• Assumption: ATS 1 transfer delay timers are configured to 5 seconds
• Assumption: ATS 2 transfer delay timers are configured to 10 seconds
• Source 1 and Source 2 are available and OK
• Now Source 1 fails
• After the transfer delay timer of ATS 1 has expired ( 5 seconds ), it will transfer Load 1 to Source 2
• After the transfer delay timer of ATS 2 has expired ( 10 seconds ), it will transfer Load 2 to Source 2
• Conclusion: Without the transfer delay timers, both ATS would transfer the load to Source 2 simultane-
ously
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