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VDWM Full form
Forward breakover voltage
Peak working forward offset voltage
Peak reverse working voltage
Peak working reverse offset voltage
Peak working forward offset voltage
VDWMтАЛ stands for Peak Working Forward Offset Voltage. It represents the maximum instantaneous voltage (excluding all non-repetitive transient voltages) that a Thyristor (SCR) can withstand in the forward blocking state without turning on.
VDWMтАЛ stands for Peak Working Forward Offset Voltage. It represents the maximum instantaneous voltage (excluding all non-repetitive transient voltages) that a Thyristor (SCR) can withstand in the forward blocking state without turning on.
VDWMтАЛ<VBOтАЛ тАФ The peak working voltage must be strictly less than the forward breakover voltage to prevent unintended triggering.
PlossтАЛ=VAKтАЛтЛЕIleakтАЛ тАФ Power dissipation related to leakage current under VDWMтАЛ.
In the forward blocking state, the inner junction J2тАЛ of the SCR is reverse-biased. The VDWMтАЛ rating defines the threshold of this reverse-biased junction's ability to maintain the blocking state while operating under rated working conditions. If the applied forward voltage exceeds this value repetitively, the leakage current increases and the SCR may experience 'breakover' due to the depletion layer width narrowing, leading to device failure or unwanted conduction.
It is a repetitive peak rating for the forward blocking mode.
It excludes non-repetitive surge voltages (VDSMтАЛ).
Essential for safe operation in AC-DC converters and inverters.
Exceeding this value leads to dv/dt triggering or thermal run-away.
Provides a clear safety margin for circuit design.
Helps in selecting appropriate snubber circuits.
Lower than VDSMтАЛ (Non-repetitive peak voltage).
Highly sensitive to junction temperature (TjтАЛ).
Industrial power supplies.
Motor drive control systems.
HVDC converter valves.
Option A is incorrect as it refers to the breakover point itself, not the working limit.
Option C refers to the reverse blocking capability (VRWMтАЛ), not forward.
Always derate these values based on the maximum operating junction temperature of the semiconductor.
B is correct тАФ VDWMтАЛ denotes the Peak Working Forward Offset Voltage, specifying the maximum repetitive forward voltage a thyristor can block.
Always distinguish between 'Working' (repetitive) and 'Surge/Non-repetitive' ratings in power electronics, as using the wrong one during design leads to catastrophic circuit failure.