inform PYRAMID DSP PREMIUM Series, Инструкция по установке и эксплуатации, Страница: 32 / 70

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Mains Limits for Bypass Operation
Frequency, rms value and total harmonic distortion of the bypass mains input voltage has to be between
acceptable limits for the UPS to operate in bypass mode.
Different rms voltage upper and lower limits are present for the return from another operation mode to
bypass mode. This provides hysteresis and ensures that the device does not change operation mode very
often when the bypass mains rms voltage is close to one of the limits.
Bypass mains limits are software parameters. They can be changed upon request.
5.2. Normal (Online) Operation
Energy is drawn from the mains input.
Loads are fed via the rectifier and the inverter. The AC voltage at the input is converted to a DC voltage by
the rectifier. The inverter converts this DC voltage to an AC voltage with a stable sinusoidal waveform,
amplitude and frequency.
Output voltage is sinusoidal and has a regulated amplitude and frequency. It is independent from the input
voltage.
The inverter is synchronized in frequency with the bypass mains input to enable load transfer to the bypass
supply without any interruption, in case of an overload or inverter failure.
Voltage and frequency of the mains input shall be in their tolerance limits, and both the rectifier and the
inverter shall be enabled for the UPS to operate in this mode.
When the upper provisions are met, the UPS works in normal (online) mode in the following conditions:
•
If the inverter priority is selected.
•
If the bypass priority is selected but bypass is disabled or frequency/waveform/rms value of bypass
mains voltage is not in acceptable limits.
Mains Limits for Normal (Online) Operation
Frequency and rms value of the mains input voltage has to be between acceptable limits for the UPS to
operate in normal (online) mode.
Lower limit of the voltage depends on how much the UPS is loaded and it decreases as the load decreases
until it reaches 80 V phase-neutral.
Frequency lower and upper limits and voltage upper limit are fixed.
Voltage and frequency ranges for normal (online) mode are given in the
Appendix-1 Technical Specifications .
This feature lessens the need to use the batteries. Thus, it increases the battery life and continuity of the
load power.
Electronic Short Circuit Protection
The UPS attempts to force the thermal/magnetic protection devices between the output terminals and the
short circuited load to open, by supplying current to the short circuited load for a limited duration. The UPS
shall be working in battery or normal mode, for this feature to work.
Bypass Operation mode does not provide electronic short circuit protection as provides in
Online Operation. If a short circuit occurs on the output during this operation, the
thermal/magnetic protection will act and all loads will be deenergized.
Prolonged overloads in Bypass Operation may cause the thermal/magnetic protection act. In
this case, all loads will be deenergized.