POWERBOX
Industrial Line
OFI1200A Series
1200W Single output
AC/DC Baseplate power supply
5
www.prbx.com
2022.07.21
Specifications are subject to change without notice.
4.3 Over current protection
The over current protection is built in and comes into effect when
drawing over 105% of the rated current.
The over current protection prevents the unit from short circuit and
over current condition. The unit automatically recovers when the fault
condition is cleared.
When the output voltage drops at over current, the average output
current is reduced by hiccup operation of the unit.
4.4 Over voltage protection
The over voltage protection circuit is built in. If the over voltage
protection circuit is activated, shut down the input voltage, wait a
certain time and turn on the AC input again to recover the output
voltage.
The recovery time is 10 seconds or more.
Remarks:
- Note that devices inside the unit might fail if voltage of higher than
rated output voltage is applied to output terminal. This could happen
when the user tests the over voltage performance of the unit.
- With option -O (Active ORing) circuit disconnects the output from the
external voltage. Therefore, over voltage protection will not be
activated. Therefore, it is not possible to test over voltage performance
for an option -O unit by applying external voltage.
4.5 Thermal protection
When the baseplate temperature exceeds the maximum temperature,
thermal protection will be activated and shut down the output.
When the thermal protection is activated, turn off the input voltage and
eliminate all the overheating conditions. To recover the output voltage,
let the unit cool down before turning on the input voltage again.
4.6 Output voltage adjustment
The output voltage can be adjusted by means of either the built-in
potentiometer (R513) or by applying an external voltage source.
(a) Adjustment by built-in potentiometer
To increase output voltage, turn R513 clockwise. To decrease the
output voltage, turn it counter clockwise.
The output voltage adjustment range by R513 is shown below.
Model
Output
Output
Number
Voltage
Voltage adj.
OFI1200A12
12VDC
4.2
–
14.4VDC
OFI1200A28
28VDC
9.8 - 33.6VDC
OFI1200A48
48VDC
16.8 - 57.6VDC
WARNING:
Adjusting the built-in potentiometer (R513) fully counter clockwise and
applying external voltage will create a short circuit that may damage
the unit.
The output voltage must be adjusted within ±20% of the nominal by
R513 before applying external voltage.
(b) Adjustment by external voltage source
To adjust the output voltage by an external voltage source, apply it
between VTRM and -S terminal.
Use a low impedance source as external voltage. The internal circuit of
VTRM is shown in Fig. 4.1.
Remarks:
- Do not apply an external voltage lower than -0.3V or greater than
5.0V.
Fig. 4.1 VTRM internal circuit
The output voltage can be calculated by the following equation when
the voltage is applied to the VTRM terminal.
Output voltage
[
V
]
=
The voltage between
VTRM and
-S [V]
2.5 [V]
×Rated output voltage [V]
Fig. 4.2 Output Voltage by VTRM
OFI1200A
VTRM
-S
5V
4.7k
Ω
10k
Ω
0.01uF
R513:
10k
External voltage source
Vref
