PowerWalker VFI 2000 RMG/S PF1 User manual

EN
PowerWalker VFI 1000 CG PF1
PowerWalker VFI 1500 CG PF1
PowerWalker VFI 2000 CG PF1
PowerWalker VFI 3000 CG PF1
PowerWalker VFI 1000 RMG/S PF1
PowerWalker VFI 1500 RMG PF1
PowerWalker VFI 2000 RMG/S PF1
PowerWalker VFI 3000 RMG PF1
Manual
Uninterruptible Power Supply System
Version: 1.4.1

Table of Contents
1. Important Safety Warning ................................................................................... 1
1-1. Transportation........................................................................................................................... 1
1-2. Preparation................................................................................................................................ 1
1-3. Installation ................................................................................................................................ 1
1-4. Operation .................................................................................................................................. 1
1-5. Maintenance, service and faults................................................................................................ 2
2. Installation and setup .......................................................................................... 3
2-1. Rear panel view ........................................................................................................................ 3
2-2. Operating principle ................................................................................................................... 4
2-3. Install the UPS (Only for RT Models)...................................................................................... 4
2-4. Setup the UPS........................................................................................................................... 5
2-5. Battery Replacement (Only for RT Models) ............................................................................ 8
2-6. Battery Kit Assembly (option for RT Models) ......................................................................... 9
3. Operations ..........................................................................................................11
3-1. Button operation ......................................................................................................................11
3-2. LCD Panel ...............................................................................................................................11
3-3. Audible Alarm......................................................................................................................... 13
3-4. LCD display wordings index.................................................................................................. 13
3-5. UPS Setting............................................................................................................................. 14
3-6. Operating Mode Description .................................................................................................. 18
3-7. Faults Reference Code............................................................................................................ 19
3-8. Warning indicator ................................................................................................................... 19
4. Troubleshooting..................................................................................................20
5. Storage and Maintenance...................................................................................21
6. Specifications .....................................................................................................22

1
1. Important Safety Warning
Please comply with all warnings and operating instructions in this manual strictly. Save this
manual properly and read carefully the following instructions before installing the unit. Do not
operate this unit before reading through all safety information and operating instructions
carefully.
1-1. Transportation
Please transport the UPS system only in the original package to protect against shock
and impact.
1-2. Preparation
Condensation may occur if the UPS system is moved directly from cold to warm
environment. The UPS system must be absolutely dry before being installed. Please
allow at least two hours for the UPS system to acclimate the environment.
Do not install the UPS system near water or in moist environments.
Do not install the UPS system where it would be exposed to direct sunlight or near
heater.
Do not block ventilation holes in the UPS housing.
1-3. Installation
Do not connect appliances or devices which would overload the UPS system (e.g.
laser printers) to the UPS output sockets.
Place cables in such a way that no one can step on or trip over them.
Do not connect domestic appliances such as hair dryers to UPS output sockets.
The UPS can be operated by any individuals with no previous experience.
Connect the UPS system only to an earthed shockproof outlet which must be easily
accessible and close to the UPS system.
Please use only VDE-tested, CE-marked (or UL-marked for 100/110/115/120/127 VAC
models) mains cable (e.g., the mains cable of your computer) to connect the UPS
system to the building wiring outlet (shockproof outlet).
Please use only VDE-tested, CE-marked (or UL-marked for 100/110/115/120/127 VAC
models) power cables to connect the loads to the UPS system.
When installing the equipment, it should ensure that the sum of the leakage current
of the UPS and the connected devices does not exceed 3.5mA.
Temperature Rating - Units are considered acceptable for use in a maximum
ambient of 40°C (104°F).
For Pluggable Equipment - The socket-outlet shall be installed near the equipment
and shall be easily accessible.
1-4. Operation
Do not disconnect the mains cable on the UPS system or the building wiring outlet
(shockproof socket outlet) during operations since this would cancel the protective
earthing of the UPS system and of all connected loads.
The UPS system features its own, internal current source (batteries). The UPS
output sockets or output terminals block may be electrically live even if the UPS
system is not connected to the building wiring outlet.
In order to fully disconnect the UPS system, first press the OFF/Enter button to
disconnect the mains.
Prevent no fluids or other foreign objects from inside of the UPS system.

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1-5. Maintenance, service and faults
The UPS system operates with hazardous voltages. Repairs may be carried out only
by qualified maintenance personnel.
Caution - risk of electric shock. Even after the unit is disconnected from the mains
(building wiring outlet), components inside the UPS system are still connected to
the battery and electrically live and dangerous.
Before carrying out any kind of service and/or maintenance, disconnect the
batteries and verify that no current is present and no hazardous voltage exists in
the terminals of high capability capacitor such as BUS-capacitors.
Only persons are adequately familiar with batteries and with the required
precautionary measures may replace batteries and supervise operations.
Unauthorized persons must be kept well away from the batteries.
Caution - risk of electric shock. The battery circuit is not isolated from the input
voltage. Hazardous voltages may occur between the battery terminals and the
ground. Before touching, please verify that no voltage is present!
Caution - Do not dispose of batteries in a fire. The batteries may explode.
Caution - Do not open or mutilate batteries. Released electrolyte is harmful to the
skin and eyes. It may be toxic.
Batteries may cause electric shock and have a high short-circuit current. Please take
the precautionary measures specified below and any other measures necessary
when working with batteries:
a) Remove watches, rings, or other metal objects.
b) Use tools with insulated handles.
c) Wear rubber gloves and boots.
d) Do not lay tools or metal parts on top of batteries.
e) Disconnect charging source and load prior to installing or maintaining the
battery.
f) Remove battery grounds during installation and maintenance to reduce
likelihood of shock. Remove the connection from ground if any part of the
battery is determined to be grounded.
When changing batteries, install the same number and same type of batteries or
battery packs.
For UPS with internally mounted battery
a) Instructions shall carry sufficient information to enable the replacement of the
battery with a suitable manufacturer and catalogue number.
b) Safety instructions to allow access by Service Personnel shall be stated in the
installation/service handbook.
c) If batteries are to be installed by Service Personnel, instructions for
interconnections, including terminal torque, shall be provided.
Do not attempt to dispose of batteries by burning them. This could cause battery
explosion.
Do not open or destroy batteries. Escaping electrolyte can cause injury to the skin
and eyes. It may be toxic.
Please replace the fuse only with the same type and amperage in order to avoid fire

3
hazards.
Do not dismantle the UPS system.
WARNING: This is a category C2 UPS product. In a residential environment, this
product may cause radio interference, in which case the user many be required to
take additional measures. (only for 220/230/240 VAC system)
2. Installation and setup
NOTE: Before installation, please inspect the unit. Be sure that nothing inside the package is
damaged. Please keep the original package in a safe place for future use.
2-1. Rear panel view
Tower Models
IEC Type
1K/1.5K 2K 3K
Rack/Tower Models
IEC Type
1K/1.5K 2K
3K

4
1. Programmable outlets: connect to non-critical loads.
2. Output receptacles: connect to mission-critical loads.
3. AC input
4. Network/Fax/Modem surge protection
5. USB communication port
6. RS-232 communication port
7. SNMP intelligent slot
8. Emergency power off function connector (EPO)
9. External battery connection
2-2. Operating principle
The operating principle of the UPS is shown as below
EMI/RFI
Filters
Battery
Charger Battery
DC-to-DC
Converter
Inverter
Rectifier
/PFC
Input Output
Dynamic
Bypass
The UPS is composed of mains input, EMI/RFI filters, rectifier/PFC, inverter, battery charger,
DC-to-DC converter, battery, dynamic bypass and UPS output.
2-3. Install the UPS (Only for RT Models)
For safety consideration, the UPS is shipped out from factory without connecting battery wires.
Before install the UPS, please follow below steps to re-connect battery wires first.
Step 1
Step 2
Step 3
Remove front panel. Connect the AC input and
re-connect battery wires.
Put the front panel back to the
unit.
This UPS can be either displayed on the desk or mounted in the 19” rack chassis. Please choose
proper installation to position this UPS.

5
Rack-mount Installation
Step 1 Step 2
Tower Installation
Step 1
Step 2
2-4. Setup the UPS
Before installing the UPS, please read below to select proper location to install UPS.
1. UPS should be placed on the flat and clean surface. Place it in an area away from vibration,
dust, humidity, high temperature, flammable liquids, gases, corrosive and conductive
contaminants. Install the UPS indoors in a clean environment, where it is away from
window and door. Maintain minimum clearance of 100mm in the bottom of the UPS to
avoid dust and high temperature.
2. Maintain an ambient temperature range of 0ºC to 45ºC for UPS optimal operation. For
every 5ºC above 45ºC, the UPS will derate 12% of nominal capacity at full load. The highest
working temperature requirement for UPS operation is 50ºC.
3. It’s required to maintain maximum altitude of 1000m to keep UPS normal operation at full
load UPS. If it’s used in high altitude area, please reduce connected load. Altitude derating
power with connected loads for UPS normal operation is listed as below:
4. Place UPS: It’s equipped with fan for cooling. Therefore, place the UPS in a well-ventilated
area. It’s required to maintain minimum clearance of 100mm in the front of the UPS and

6
300mm in the back and two sides of the UPS for heat dissipation and easy maintenance.
5. Connect to External Battery Pack
When connecting external battery packs, please be sure to connect polarity correctly.
Connect positive pole of battery pack to positive pole of external battery connector in UPS
and negative pole of battery pack to negative pole of external battery connector in UPS.
Polarity misconnection will cause UPS internal fault. It’s recommended to add one breaker
between positive pole of battery pack and positive pole of external battery connector in UPS
to prevent damage to battery packs from internal fault.
The required specification of breaker: voltage ≧1.25 x battery voltage/set; current ≧50A
Please choose battery size and connected numbers according to backup time requirement
and UPS specifications. To extend battery lifecycle, it’s recommended to use them in the
temperature range of 15ºC to 25ºC.
Step 1: External battery connection
Follow the right chart to make external battery connection.
Step 2: UPS input connection
Plug the UPS into a two-pole, three-wire, grounded receptacle only. Avoid using extension
cords.
For 200/208/220/230/240VAC models: The power cord is supplied in the UPS package.
Note: Check if the site wiring fault indicator lights up in LCD panel. It will be illuminated when
the UPS is plugged into an improperly wired utility power outlet (Refer to Troubleshooting
section). Please also check if there is a circuit breaker against overcurrent and short circuit
between the mains and AC input of the UPS for safety operation. The recommended protection
value as following:
For 200/208/220/230/240VAC models: 10A for the 1K and 1.5K models, 16A for the 2K
and 3K models.
Step 3: UPS output connection
There two kinds of outputs: programmable outlets and general outlets. Please connect non-
critical devices to the programmable outlets and critical devices to the general outlets. During
power failure, you may extend the backup time to critical devices by setting shorter backup
time for non-critical devices.

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Step 4: Communication connection
Communication port:
USB port RS-232 port Intelligent slot
To allow for unattended UPS shutdown/start-up and status monitoring, connect the
communication cable one end to the USB/RS-232 port and the other to the communication
port of your PC. With the monitoring software installed, you can schedule UPS
shutdown/start-up and monitor UPS status through PC.
The UPS is equipped with intelligent slot perfect for either SNMP or AS400 card. When
installing either SNMP or AS400 card in the UPS, it will provide advanced communication and
monitoring options.
Step 5: Network connection
Network/Fax/Phone surge port
Connect a single modem/phone/fax line into surge-protected “IN” outlet on the back panel of
the UPS unit. Connect from “OUT” outlet to the equipment with another modem/fax/phone
line cable.
Step 6: Disable and enable EPO function
This UPS is equipped with EPO function. By default, the UPS is delivered from factory with
Pin 1 and pin 2 closed (a metal plate is connected to Pin 1 and Pin2) for UPS normal
operation. To activate EPO function, remove two screws on EPO port and metal plate will be
removed.
Note: The EPO function logic can be set up via LCD setting. Please refer to program 16 in
UPS setting for the details.
Step 7: Turn on the UPS
Press the ON/Mute button on the front panel for two seconds to power on the UPS.
Note: The battery charges fully during the first five hours of normal operation. Do not
expect full battery run capability during this initial charge period.
Step 8: Install software
For optimal computer system protection, install UPS monitoring software to fully configure
UPS shutdown. Use supplied RS-232 or USB communication cable to connect RS-232/USB
port of UPS and RS-232/USB port of PC. Then, follow below steps to install monitoring
software.
It’s in closed status for UPS
normal operation as default.
To activate EPO function,
remove these two screws.

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1. Insert the included installation CD into CD-ROM drive and then follow the on-screen
instructions to proceed software installation. If there no screen shows 1 minute after
inserting the CD, please execute setup.exe file for initiating software installation.
2. Follow the on-screen instructions to install the software.
3. When your computer restarts, the monitoring software will appear as an orange plug icon
located in the system tray, near the clock.
2-5. Battery Replacement (Only for RT Models)
NOTICE: This UPS is equipped with internal batteries and user can replace the batteries
without shutting down the UPS or connected loads.(hot-swappable battery design)
Replacement is a safe procedure, isolated from electrical hazards.
CAUTION!! Consider all warnings, cautions, and notes before replacing batteries.
Note: Upon battery disconnection, equipment is not protected from power outages.
Step 1
Step 2
Step 3
Remove front panel. Disconnect battery wires. Pull out the battery box by
removing two screws on the
front panel.
Step 4
Step 5
Step 6
Remove the top cover of
battery box and replace the
inside batteries.
After replacing the
batteries, put the battery
box back to original
location and screw it
tightly.
Re-connect the battery wires.
Step 7
Put the front panel back to the unit.

9
2-6. Battery Kit Assembly (option for RT Models)
NOTICE: Please assemble battery kit first before installing it inside of UPS. Please select
correct battery kit procedure below to assemble it.
2-battery kit
Step 1: Remove adhesive tapes. Step 2: Connect all battery terminals by
following below chart.
Step 3: Put assembled battery packs on
one side of plastic shells.
Step 4: Cover the other side of plastic shell as
below chart. Then, battery kit is assembly well.
3-battery kit
Step 1: Remove adhesive tapes. Step 2: Connect all battery terminals by
following below chart.
Step 3: Put assembled battery packs on
one side of plastic shells as below chart.
Step 4: Cover the other side of plastic shell as
below chart. Then, battery kit is assembly well.
Tap e s
Tap e s
Tap e s

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4-battery kit
Step 1: Remove adhesive tapes. Step 2: Connect all battery terminals by
following below chart.
Step 3: Put assembled battery packs on
one side of plastic shells.
Step 4: Cover the other side of plastic shell as
below chart. Then, battery kit is assembly well.
6-battery kit
Step 1: Remove adhesive tapes. Step 2: Connect all battery terminals by
following below chart.
Step 3: Put assembled battery packs on
one side of plastic shells.
Step 4: Cover the other side of plastic shell as
below chart. Then, battery kit is assembly well.
Tap e s
Tap e s
Tap e s
Tap e s

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3. Operations
3-1. Button operation
Button Function
ON/Mute
Button

Turn on the UPS: Press and hold ON/Mute button for at least 2
seconds to turn on the UPS.
Mute the alarm: After the UPS is turned on in battery mode, press and
hold this button for at least 3 seconds to disable or enable the alarm
system. But it’s not applied to the situations when warnings or errors
occur.
Up key: Press this button to display previous selection in UPS setting
mode.
Switch to UPS self-test mode: Press ON/Mute buttons for 3 seconds to
enter UPS self-testing while in AC mode, ECO mode, or converter
mode.
OFF/Enter
Button

Turn off the UPS: Press and hold this button at least 2 seconds to turn
off the UPS. UPS will be in standby mode under power normal or
transfer to Bypass mode if the Bypass enable setting by pressing this
button.
Confirm selection key: Press this button to confirm selection in UPS
setting mode.
Select
Button

Switch LCD message: Press this button to change the LCD message
for input voltage, input frequency, input current, battery voltage,
battery current, battery capacity, ambient temperature, output
voltage, output frequency, load current and load percent.
Setting mode: Press and hold this button for 3 seconds to enter UPS
setting mode when Standby and Bypass mode.
Down key: Press this button to display next selection in UPS setting
mode.
ON/Mute
+ Select
Button

Switch to bypass mode: When the main power is normal, press
ON/Mute and Select buttons simultaneously for 3 seconds. Then UPS
will enter to bypass mode. This action will be ineffective when the
input voltage is out of acceptable range.
Exit setting mode or return to the upper menu: When working in
setting mode, press ON/Mute and Select buttons simultaneously for
0.2 seconds to return to the upper menu. If it’s already in top menu,
press these two buttons at the same time to exit the setting mode.
3-2. LCD Panel

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Display
Function
Backup time information
Indicates the estimated backup time.
H: hours, M: minute, S: second.
Configuration and fault information
Indicates the configuration items, and the configuration items are listed
in details in section 3-5.
Indicates the warning and fault codes, and the codes are listed in details
in section 3-7 and 3-8.
Mute operation
Indicates that the UPS alarm is disabled.
Input, Battery, Temperature, Output & Load information
IIndicate the input voltage, input frequency, input current, battery
voltage, battery current, battery capacity, ambient temperature, output
voltage, output frequency, load current and load percent.
k: kilo, W: watt, V: voltage, A: ampere, %: percent,
℃
: centigrade degree, Hz: frequency
Load information
Indicates the load level by 0-24%, 25-49%, 50-74% and 75-100%.
Indicates overload.
Programmable outlets information
Indicates that programmable management outlets are working.
Mode operation information
Indicates the UPS connects to the mains.
Indicates the battery is working.
Indicates charging status
Indicates the bypass circuit is working.
Indicates the ECO mode is enabled.
Indicates the AC to DC circuit is working.
Indicates the PFC circuit is working.
Indicates the inverter circuit is working.
Indicates the UPS is working in converter mode.
Indicates the output is working.
Battery information
Indicates the battery level by 0-24%, 25-49%, 50-74%, and 75-100%.
Indicates low battery.

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3-3. Audible Alarm
Battery Mode
Sounding every 5 seconds
Low Battery Sounding every 2 seconds
Overload
Sounding every second
Fault
Continuously sounding
Bypass Mode
Sounding every 10 seconds
3-4. LCD display wordings index
Abbreviation
Display content
Meaning
ENA
Enable
DIS
Disable
ESC
Escape
HLS
High loss
LLS
Low loss
AO
Active open
AC
Active close
EAT
Estimated autonomy time
RAT
Running autonomy time
SD
Shutdown
OK
OK
ON
ON
BL
Battery Low
OL
Over Load
OI
Over input current
NC
Battery No Connect
OC
Over Charge
SF
Site wiring fault
EP
EPO
TP
Temperature
CH
Charger
BF
Battery Fault
BV
Bypass Out Range
FU
Bypass frequency unstable
BR
Battery Replace
EE
EEPROM error

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3-5. UPS Setting
Parameter 1Parameter 2
There are three parameters to set up the UPS.
Parameter 1:
It’s for program alternatives.
Refer to below table.
Parameter 2 is the setting options or values
for each program
01: Output voltage setting
Interface
Setting
Parameter 2: Output voltage
For 200/208/220/230/240 VAC models, you may choose
the following output voltage:
200: presents output voltage is 200Vac
208: presents output voltage is 208Vac
220: presents output voltage is 220Vac
230: presents output voltage is 230Vac (Default)
240: presents output voltage is 240Vac
02: Frequency Converter enable/disable
Interface
Setting
Parameter 2: Enable or disable converter mode. You may
choose the following two options:
CF ENA: converter mode enable
CF DIS: converter mode disable (Default)
03: Output frequency setting
Interface
Setting
Parameter 2: Output frequency setting.
You may set the initial frequency on battery mode:
BAT 50: presents output frequency is 50Hz
BAT 60: presents output frequency is 60Hz
If converter mode is enabled, you may choose the following
output frequency:
CF 50: presents output frequency is 50Hz
CF 60: presents output frequency is 60Hz
04: ECO enable/disable
Interface
Setting
Parameter 2: Enable or disable ECO function. You may
choose the following two options:
ENA: ECO mode enable
DIS: ECO mode disable (Default)

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05: ECO voltage range setting
Interface
Setting
Parameter 2: Set the acceptable high voltage point and
low voltage point for ECO mode by pressing Down key or
Up key.
HLS: High loss voltage in ECO mode in parameter 2.
For 200/208/220/230/240 VAC models, the setting range in
parameter 3 is from +7V to +24V of the nominal voltage.
(Default: +12V)
LLS: Low loss voltage in ECO mode in parameter 2.
For 200/208/220/230/240 VAC models, the setting range in
parameter 3 is from -7V to -24V of the nominal voltage.
(Default: -12V)
06: Bypass enable/disable when UPS is off
Interface
Setting
Parameter 2: Enable or disable Bypass function. You
may choose the following two options:
ENA: Bypass enable
DIS: Bypass disable (Default)
07: Bypass voltage range setting
Interface
Setting
Parameter 2: Set the acceptable high voltage point and
acceptable low voltage point for Bypass mode by pressing
the Down key or Up key.
HLS: Bypass high voltage point
For 200/208/220/230/240 VAC models:
230-264: setting the high voltage point in parameter 3
from 230Vac to 264Vac. (Default: 264Vac)
LLS: Bypass low voltage point
For 200/208/220/230/240 VAC models:
170-220: setting the low voltage point in parameter 3
from 170Vac to 220Vac. (Default: 170Vac)
08: Bypass frequency range setting
Interface
Setting
Parameter 2: Set the acceptable high frequency point
and acceptable low frequency point for Bypass mode by
pressing the Down key or Up key.
HLS: Bypass high frequency point
For 50Hz output frequency models:
51-55Hz: setting the frequency high loss point from
51Hz to 55HZ(Default: 53.0Hz)
For 60Hz output frequency models:
61-65Hz: setting the frequency high loss point from
61Hz to 65Hz(Default: 63.0Hz)
LLS: Bypass low Frequency point

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For 50Hz output frequency models:
45-49Hz: setting the frequency low loss point from 45Hz to
49HZ(Default: 47.0Hz)
For 60Hz output frequency models:
55-59Hz: setting the frequency low loss point from 55Hz to
59Hz(Default: 57.0Hz)
09: Programmable outlets enable/disable
Interface
Setting
Parameter 2: Enable or disable programmable outlets.
ENA: Programmable outlets enable
DIS: Programmable outlets disable (Default)
10: Programmable outlets setting
Interface
Setting
Parameter 2: Set up backup time limits for
programmable outlets.
0-999: setting the backup time limits in minutes from 0-
999 for programmable outlets which connect to non-
critical devices on battery mode. (Default: 999)
11: Autonomy limitation setting
Interface
Setting
Parameter 2: Set up backup time on battery mode for
general outlets.
0-999: setting the backup time in minutes from 0-999
for general outlets on battery mode.
DIS: Disable the autonomy limitation and the backup
time will depend on battery capacity. (Default)
Note: When setting as “0”, the backup time will be only
10 seconds.
12: Battery total AH setting
Interface
Setting
Parameter 2: Set up the battery total AH of the UPS.
7-999: setting the battery total capacity from 7-999 in
AH. Please set the correct battery total capacity if
external battery bank is connected.
13: Maximum charger current setting
Interface
Setting
Parameter 2: Set up the charger maximum current.
For low voltage model with 24/36/48VDC
1/2/4/6/8:setting the charger maximum current
1/2/4/6/8 in Ampere. (Default: 2A)
For high voltage model with 24/36/48VDC
1/2/4/6/8/10/12:setting the charger maximum
current 1/2/4/6/8/10/12 in Ampere. (Default: 2A)

17
For low voltage and high voltage model with 72/96VDC
1/2/4/6/8:setting the charger maximum current
1/2/4/6/8 in Ampere. (Default: 2A)
Note: Please set the appropriate charger current based on
battery capacity used. The recommended charging
current is 0.1C~0.3C of battery capacity as following table
for reference.
Battery capacity(AH)
Total charging current (A)
7~20
2
20~40
4
40~60
6
60~80
8
80~100
10
100~150
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14: Charger boost voltage setting
Interface
Setting
Parameter 2: Set up the charger boost voltage.
2.25-2.40:setting the charger boost voltage from 2.25
V/cell to 2.40V/cell. (Default: 2.36V/cell)
15: Charger float voltage setting
Interface
Setting
Parameter 2: Set up the charger float voltage.
2.20-2.33:setting the charger float voltage from 2.20
V/cell to 2.33V/cell. (Default: 2.28V/cell)
16: EPO logic setting
Interface
Setting
Parameter 2: Set up the EPO function control logic.
AO: Active Open (Default). When AO is selected as EPO
logic, it will activate EPO function with Pin 1 and Pin 2 in
open status.
AC: Active Close. When AC is selected as EPO logic, it will
activate EPO function with Pin 1 and Pin 2 in close status.
17: External output isolation transformer connection
Interface
Setting
Parameter 2: Allow or disallow external output isolation
transformer connection.
ENA: If selected, it’s allowed to connect to an external
output isolation transformer.
DIS: If selected, it’s not allowed to connect to external
output isolation transformer. (Default)