Toshiba 1800 manual Appendix C Parallel Operation, Parallell Running Input Power vs. Input Voltage

Appendix C: Parallel Operation

The 1800 Series UPS offers a standard feature that allows the unit to operate with very low input voltage without de-rating the output power. If the input voltage drops below a certain point the unit will switch to parallel mode. Parallel mode means that the unit is using the available input voltage and supplementing with battery power. Because battery power is being used, the time the unit can operate in parallel mode is limited. However, the time will be longer than that available when the unit is operating on battery power alone.

The point when the UPS will enter parallel mode will vary depending on the output load. The following graph illustrates the UPS’ transition from battery to line power as the line voltage increases from 40% to 100% of normal. Transition curves are shown for 75% and 100% output load.

Parallell Running: Input Power vs. Input Voltage

	120
	100
			AC Input
(%)	80
Input Power	60
	40
	20		Battery
	0
	40	55	70	85

Input Voltage (%)

100% Load

75% Load

As shown in the graph, the lower the output load, the lower the input voltage can go before parallel mode is activated. However, the minimum input voltage will always remain at 60% (72 VAC for a 120 VAC system).

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