Overvoltage protection

It is easy to notice, that the protection against a short-circuit failure in the X-ray tube circuit implements due to the "soft" outer characteristic of the apparatus main circuit. The overvoltage protection at emergencies in the control system happens due to the redistribution of the magnetie flow, created by power winding I, between the 3,6 control yokes. Therefore the voltage on the X-ray apparatus anode drops approximately two times. 

All these drives are based on pulse width modulation (PWM) and hence would produce overvoltages at the inverter output and require overvoltage protection for cable lengths of 100 m (typical) and above, depending upon the steepness of the wave (Section 6.14.1). 

General Electric Company. USA. Travsmissiou. October 1971 (overvoltage protection). 

In such eases, the overvoltage protection may still be set for 10% and even less, to contain the fault. It is a recommended practice to provide OV protection on the failure of only one half of a unit, to limit the damage to a very low extent. 

Figure 26.11 Overvoltage protection with the help of a spark gap and a shorting switch...

This part is complementary to Part II and provides technical support to switchgear assemblies and machines fed by them for surge and overvoltage protection. It is a very useful part for all those handling HV and EHV power systems and their surge and overvoltage protection. 

Fig. 8-4 Circuit diagram of a transformer-rectifier with overvoltage protection (protected against high voltage).

Contact Voltage Protection Overvoltage protection against ... 

Figure 3-52 Overvoltage protection schemes (a) Zener diode clamp (b) overvoltage crowbar (c) precision overvoltage crowbar.

Overvoltage Protection. Devices such as overvoltage relays provide a reduction in the level of apphed voltage or a maintained interruption of power to the motor circuit when excessive voltage levels are experienced. High induced voltages may occur as a result of the interruption of inductive motor control circuits. 

EFS designers need to know enough about their equipment s environment (EM physical climatic wear ageing, etc. over the anticipated lifecycle) and foreseeable faults and misuse, to select appropriately-rated components, and to design circuits, software, filtering, shielding, overvoltage protection, etc. They need this... 

In addition, it is necessary to protect the digital ICs from overvoltage an overvoltage protection circuit is introduced. 

If you suspect that the overvoltage protection has become active, you should switch off Che instruments, and connect it via a VARIAC to the mains, as shown in Fig. 5.5. Increase slowly the voltage Co Che instrument. In this way it is possible Co distinguish if there was a bad adjustment of the overvoltage protection or if a transient occurred during the switching on of Che instrument. 

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