© 2016 OJ Electronics A/S
20
INSTRUCTIONS OJ-DV | Functions
OJ-DV can be set to operate constantly with a switching frequency of either 4 kHz or 8 kHz, or it
can be set to change switching frequency automatically depending on motor speed (AUTO setting).
Switching frequency (switching mode) is set via Modbus:
• Setting ”4kHz” = Constant 4kHz switching frequency
• Setting ”8kHz” = Constant 8kHz switching frequency
• Setting ”AUTO” = Switching frequency is changed automatically:
• At motor speeds higher than 60% of rated speed, switching frequency is changed to 4 kHz
• At motor speeds lower than 50% of rated speed, switching frequency is changed to 8 kHz
18.4 Braking power
• The electronics within OJ-DV can as a starting point supply braking power corresponding to its
own consumption. It is expected that an air flow capable of maintaining typically up to 30% of
nominal fan speed can be braked by this function.
18.5 Fire mode
• Fire mode designates a function in which OJ-DV is kept operating by an emergency program
which disables the alarm monitor.
• The fire mode function can be activated via Modbus or via digital input.
• Among other things, the function can be used in connection with smoke extraction from a burning
property. When fire mode is activated, an extraction fan will continue to remove smoke from the
property for as long as possible.
• In fire mode, OJ-DV is able to maintain operation for at least an hour even when OJ-DV and the
fan motor are overheated (max. 70°C).
• Upon activation of fire mode operation the output signal to the motor remains the same value as it
was just before the fire mode condition was activated, and any alarms will be suppressed.
• During fire mode operation the output signal to the motor will at any time be the selected voltage
of 0-10V input, or if the OJ-DV is controlled via Modus, it will be the control signal from a potential
Modbus Master. If there is a communication failure on the Modbus, the output signal to the motor
will be the same value as it was just before the Modbus communication was disconnected.
• If the motor is not operating when fire mode is activated, the motor will remain stopped upon
activation of fire mode.
18.6 Frequency converter mode – for asynchronous motors
Figure 18.6.1
BR1014A41a
© 2016 OJ Electronics A/S
BR1014A41a
The OJ-DV factory-set to frequency converter mode for
standard asynchronous induction motors (AC-IM) and
the control mode is 0-10VDC input.
This can be changed using the OJ-DV-PCTool or OJ-
DCV-HTERM (Hand terminal).
If you use the OJ-DV in frequency converter mode, you
must connect a standard 3 phase~ AC-IM motor. Pay
special attention to the information that you will find on
the nameplate of the motor.
The voltage output from the OJ-DV is for the OJ-
DV-1005…..OJ-DV-1011 maximum 250 VAC.
For the OJ-DV-3015…..OJ-DV-3150 the maximum
voltage output is 364 VAC.
If the supply voltage is higher than the rated voltage of
the single windings in the connected motor, then the
motor will be damaged.
Pay special attention if the motor is connected in “star”
or “delta” connections.
On a standard AC-IM motor, the “star”/“delta”
connection often can be changed by rearranging
the jumpers on the motor terminal, see figure 18.6.
With the OJ-DV in frequency converter mode, it is the
installer’s responsibility to enter the correct control and
motor parameters.
To Next Page
Loading...
Need help?
General
