DNH DHVC5000 Series, Use Manual

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4 Chapter 4 Fault Diagnosis
4.1 Fault Query
When a Medium Voltage MVC shuts down due to a fault, the following method should be
used for fault analysis:
 View the fault description on the control cabinet touch screen.
 Confirm the cause of the power unit fault from the indicator lights on the power unit
board.
 Fault information may also be exported via USB to a PC for review.
4.2 Troubleshooting
The DNH DHVC series MVC has a perfect protection function so as to protect the equipment
against damage under abnormal conditions. When the MVC is in a fault state, all IGBTs will be
blocked, so that the motor has no power and will freewheel to a stop, the MCGS TPC saves and
displays the fault record on the touch screen of the control cabinet.
When a MVC fails, the operator on site should record the input voltage, voltage on the DC
side, output voltage, output current and fault information etc at the moment of the fault, and carry
out a preliminary analysis based on the fault record.
4.3 Causes of Faults, Alarms And Their Remedies
Table 4-1 Fault Information Table
Fault Display Type Probable Fault Cause Remedy
Primary
Overvoltage Alarm
Effective value of MVC input
voltage exceeds the setpoint
1. Eliminate the factors that cause too high a
voltage on the input side
2. Check voltage sensor and its wiring
3. Check sensor factorand the overvoltage level
parameter settings
4. Replace the analog circuit Board, CPU circuit
Board
Secondary
Overvoltage Alarm
Effective value of MVC input
voltage exceeds the setpoint
Tertiary
Overvoltage
Fault
Effective value of MVC input
voltage exceeds the setpoint
Instantaneous
Overvoltage
Fault
Effective value of MVC input
voltage exceeds the setpoint
Primary
Undervoltage Alarm
MVC input voltage is lower than
the setpoint
1. Eliminate the factors that cause too low a
voltage on the input side
2. Check the voltage sensor and its wiring
3. Check the sensor and the undervoltage level
parameter setting
4. Replace the analog board card, CPU board card
Secondary
Undervoltage Alarm
MVC input voltage is lower than
the setpoint
Tertiary
Undervoltage
Fault
MVC input voltage is lower than
the setpoint
Voltage
Unbalance
Fault
Software detects the MVC input
(line) voltage three-phase unbalance
beyond the setpoint 1. Check the sensor and its wiring
2. Check whether the Grid side input three-phase
voltage is balanced on site
3. Check the unbalance setting
Input Open Phase Fault
One or more input medium voltage
cable(s) could not supply power to
the input transformer
1. Check sensor and its wiring
2. Check whether the open phase of higher level
input voltage is true on site
3. Check the sensor setting