Liebert® Series 610™ UPS - Jonweb.net
Liebert® Series 610™ UPS - Jonweb.net
Liebert® Series 610™ UPS - Jonweb.net
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Theory of Operation<br />
Transfer and Retransfer Conditions<br />
1. Automatic Transfers to Bypass<br />
Critical bus conditions that will initiate an automatic transfer of the critical load from the <strong>UPS</strong><br />
system to the bypass source are:<br />
a. System Overload: overcurrent condition in excess of the overload rating of the System Control<br />
Cabi<strong>net</strong> (SCC).<br />
b. Output Overload: overcurrent condition in excess of the current-versus-time overload capacity<br />
of <strong>UPS</strong> modules ON LINE.<br />
c. Overvoltage/Undervoltage (OV/UV): critical bus voltage is outside the allowable tolerance.<br />
d. Non-redundant <strong>UPS</strong> Module Inoperative: an essential <strong>UPS</strong> module is taken OFF LINE for<br />
one of the reasons below.<br />
1. Battery discharged to the shutdown voltage.<br />
2. Inverter overload capacity exceeded.<br />
3. Inverter or rectifier fault condition (power, logic or overtemperature) present or<br />
imminent.<br />
4. Failure of <strong>UPS</strong> module logic or logic power.<br />
e. SCC Logic:<br />
1. Emergency Module Off (EMO) circuit activated.<br />
2. Failure of <strong>UPS</strong> system logic or logic power.<br />
2. Manual Transfers<br />
Manual transfers may be initiated at any time provided no transfer inhibition conditions are<br />
present.<br />
3. Transfer Inhibited<br />
A manual transfer to the bypass source will be inhibited if any of the following conditions exist:<br />
a. <strong>UPS</strong> system to bypass voltage difference (ΔV) exceeds a predetermined percentage (normally<br />
5%).<br />
b. Static switch disconnects open.<br />
c. OK to Transfer signal from the control logic is not present.<br />
NOTE<br />
A load transfer to the bypass line will be completed whenever an automatic transfer to bypass<br />
is initiated. If the Static Switch Unable alarm message is present for any reason (including a<br />
±20° phase lock synchronization error), the automatic transfer will be interrupted for<br />
40-120 milliseconds. Because of the reliability of the <strong>UPS</strong> components, an interrupted load<br />
transfer is a very unlikely occurrence.<br />
4. Automatic Retransfers to <strong>UPS</strong><br />
Critical bus conditions that must be present to initiate an automatic retransfer (Auto-Rexfer) of<br />
the critical load from the bypass source to the <strong>UPS</strong> system are:<br />
a. The number of Auto-Rexfer Attempts selected must be greater than zero (0). If zero (0) is<br />
selected, no automatic retransfer will occur.<br />
b. Critical load was initially transferred to the bypass source due to a system overload only.<br />
c. Overload has since dropped below 100% of the rated SCC current.<br />
d. Enough <strong>UPS</strong> modules are ON LINE to supply the critical load.<br />
e. OK to Transfer signal received from the control logic for at least 10 seconds, within 5 minutes<br />
of the overload transfer. (A manually initiated retransfer from bypass is required for<br />
overloads lasting 5 minutes or more.)<br />
f. Cyclic-type system overloads, which occur up to five (select range is 0 to 5) times in<br />
60 minutes, are automatically returned to the <strong>UPS</strong> system for each event including the Nth<br />
overload. A manually initiated retransfer from bypass is required for the N+1 overload.<br />
5. Manual Retransfers<br />
Manual retransfers may be initiated at any time provided no retransfer inhibition conditions are<br />
present.<br />
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