Product Manual

74 | SAMLEX AMERICA INC.
o When Grid / Generator input power fails, Relay RY2 (Fig 4.1) will be de-energized and
contact 4 switches back to contact 3. Neutral output from the Inverter Section is fed the
Neutral of the Bi-directional Transformer and onwards to the output Neutral (OUTPUT
N) for powering the AC loads. At the same time, the output Neutral (OUTPUT N) gets
bonded to the metal chassis of the unit through the mated contacts of the Insulated
Male / Female Quick Disconnect (27, Fig 4.1) located in the AC Wiring Compartment
[27, Fig 3.9.2(a)] in EVO-1212F-HW / 1224F-HW. In EVO-1212F / 1224F, the Insulated
Male / Female Quick Disconnect is accessible after opening the top cover of the unit.
NEUTRAL
BI-DIRECTIONAL
TRANSFORMER
LINE
RY2
RY1
METAL CHASSIS
GROUND OF THE EVO
TM
3
4
5
3
4
5
INVERTING
CHARGING
OUTPUT N
INPUT L
INPUT
GND
INPUT N
OUTPUT L
OUTPUT
GND
27
Fig 4.1 Operation of Transfer Relay and Neutral to Ground Bond Switching
LEGEND for Fig 4.1
RY1 Transfer Relay (30A) (Shown in de-energized state). Transfers the Line Conductor of
the AC load to either the Line Conductor of the input from Grid / Generator or to
the Line Conductor of the Inverter Section.
RY2 Relay (30A) for Neutral to Ground bond Switching
4, 3 Normally Closed Contacts (Shown in de-energized state)
4, 5 Normally Open Contacts (Shown in de-energized state)
27 Insulated Male / Female Quick Disconnect [27, Fig 3.9.2(a)] for disconnecting
Output Neutral to Chassis Ground bond in Inverting Mode (Default - connected)
NOTE: Relays are de-energized in Inverting Mode and are energized in Charging Mode
4.4.3 Synchronized Transfer of Power – Inverter to AC Input Source
Assume that AC input power source (from Grid / Generator) is not available and the unit is
working in "Inverting Mode".
When AC input power becomes available, its voltage and frequency are checked if these are
within the programmed limits. If yes, the frequency and phase of the Inverter Section are
SECTION 4 | General Description & Principles of Operations