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4.5.2.1.3
Transfer From Inverter Section to AC Input Source
When power from AC input source is made available, its voltage and frequency are monitored for 2 sec to check if
these are within the programmed limits. If yes, the output voltage of the Inverter Section is synchronized with the
AC input source. This synchronization process takes few seconds. Once synchronization is completed, the load is
transferred instantly (
within 1 ms
) to the AC input source at Zero Crossing of the voltage waveform for safer transfer
and for better protection of Transfer Relay contacts. The unit now operates in “Charging Mode” with the AC power
from the AC input source charging the batteries as well as providing power to the AC loads.
4.5.2.1.4
Transfer From AC Input Source to Inverter Section
When the unit is operating in “Charging Mode” with the AC input source charging the batteries as well as passing
through power to the AC loads, the phase and frequency of the AC input source are tracked continuously. In case
AC input source fails or is disconnected, the inverter will be forced to transfer at voltage which is at the same phase
and frequency at which the AC input source had been disconnected. Load will be transferred to the inverter within
18ms at zero crossing. The unit will now work in “Inverting Mode” and the batteries will start discharging.
4.6 BATTERY CHARGER SECTION
The Battery Charger Section of this unit provides 2/3/4 stage charging with 7 programmable charging profiles as
detailed at Section 5.6. The same Isolation Transformer and the H-Bridge configuration of the Inverter Section are
used to work in the reverse direction, i.e. the AC input is stepped down and rectified to the programmed DC battery
charging voltage using Pulse Width Modulation (
PWM
) Control. That is why it is called a Bi-directional device. Further,
the charging voltages and currents are programmable to take care of a wide range of battery types like Lead Acid,
Nickel-Zinc (
Ni-Zn
) & Lithium Ion.
Important battery charging features are as follows:
• Adaptive Charging Control for 2 Charging Profiles out of the 7 profiles
• Dynamic Input Power Diversion Control
• Parallel charging through External Charge Controller
• Temperature compensated charging
• Programmable Charging Profiles for Lead Acid, Nickel-Zinc (
Ni-Zn
) and Lithium Batteries
Please see details under Section 5 titled “Battery Charging in Evolution
TM
Series”.
4.7 AUTO GENERATOR START / STOP FOR OFF GRID APPLICATION
In off-grid applications, a backup generator is normally used to charge the batteries in case of inadequacy of solar
power to keep the batteries charged above the threshold of Battery Low Voltage Shutdown of the Inverter.
Auto Generator Start / Stop function has been provided using “Common” and Normally Open “NO” contacts
of Status Relay (
14, Fig 2.1
). The relay is SPDT Type with contacts rated at 3A, 125 VAC / 30 VDC. Appropriate
external Generator Auto Start / Stop Module will be required for using this function. 3 options (
Options 2, 3 and 4
under programming parameter "RELAY FUNCTION"
) are available for carrying out this function depending upon user
requirements.
For details, please refer to Section 4.8.2.5.2 in the EVO-RC-PLUS Remote Control Manual.
The “Common” and “NO” terminals are wired to the optional Generator Auto Start / Stop Control Module which,
in turn, is wired to the Remote Start / Stop connections on the Generator. The AC output terminals of the Generator
are wired to the AC Input Terminals on the EVO™ (
2,3,4 in Fig 3.9
).
SECTION 4 |
General Description & Principles of Operation
Summary of Contents for Evolution EVO-4248SP
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