SamplexPower PSR-1200-24, Руководство пользователя, Страница: 15 / 100

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5.2 POWER SECTIONS OF THE SYSTEM
The unit consists of 2 Power Sections – (i) DC to AC Inverter Section and (ii) Transfer Relay Section.
AC / DC input and output power arrangements are as follows:
• 100-120VAC, 50/60Hz from the Grid / Generator is fed to the unit through 120VAC Male Power Inlet
Connector IEC 60320 C14 (18, Fig 6.2). The AC input is protected against over current through 12A
Breaker (19, Fig 6.2)
• DC power from 24V / 48VDC battery bank is fed to the DC Input Terminals (10. 11 at Fig 6.2) through
external fuse
• AC output power is fed through NEMA5-20 Duplex AC outlet (17, Fig 6.2)
5.3 DC-AC INVERTER SECTION
The Inverter Section is a micro-controller based, high efficiency, Pure Sine Wave Inverter (THD < 2%). It
converts 24V / 48V DC voltage from batteries to 120VAC, 50/60Hz AC voltage (Default). The AC output
voltage is programmable within a range of 100 to 120VAC (Default is 120VAC) and the AC output
frequency is programmable within a range of 45 to 65 Hz (Default is 60Hz). This enables its usage in
multiple countries with national Grid voltages ranging from 100 to 120VAC and 50/60 Hz frequency (e.g.
North America, Taiwan, Japan etc).
DC to AC voltage conversion takes place in two stages. In the First Stage, the DC voltage of the battery is
converted to high voltage DC using high frequency switching and PWM (Pulse Width Modulation) technique.
In the second stage, the high voltage DC is converted to 120VAC (Default), 60Hz (Default) pure sine wave AC
again using PWM technique. This is done by using special wave shaping technique where the high voltage DC
is switched at high frequency and the pulse width of switching is modulated with respect to reference sine
wave. High frequency components are then filtered to get modulated pure sine wave form.
5.3.1 No Load Draw / Idle Current in Inverter Mode
When the Inverter Section is turned ON, all the circuitry in the Inverter Section becomes alive. In this
condition, even when no load is being supplied by the Inverter Section (or if the load is connected but has
not been switched ON), it draws a small amount of current from the batteries to keep the circuitry alive
and ready to deliver the required power on demand. This current is called the “No Load Current” or the
“Idle Current” of the Inverter Section. The specified values for this current are as follows”:
• PSR-1200-24: < 0.6A
• PSR-1200-48: < 0.5A
i
INFO
When the Inverter Section is turned OFF but AC GRID input is still available, AC GRID input voltage
will be bypassed to the load through the closed contacts of the energized Relays RL-1 and RL-
2 and the Normally Closed (NC) contacts of the de-energized Relays RL-4 and RL-5( see Fig. 5.1).
Relays RL-1 and RL-2 are energized by +12VDC generated by a small Switch Mode Power Supply
(SMPS) that is powered from the AC GRID input and NOT from the batteries. Hence, in this
condition, there will be no current draw from the batteries.
SECTION 5 | Description & Principles of Operation