Dr Kesorn Pechrach Weaver: Piezoelectrics in Circuit Breakers: Contact speed setup

Dr Kesorn Pechrach Weaver: Piezoelectrics in Circuit Breakers: Contact speed setup: 5.1 Contact speed setup The opening contact mechanism was modified to reduce contact speed from 10 m/s down to 1 m/s. There are tw...

Contact speed setup

5.1 Contact speed setup

The opening contact mechanism was modified to reduce contact speed from 10 m/s down to 1 m/s. There are two important parts in this system. The first part is the instrument to measure the speed of contact and the second part is the instrument to control the speed. The instrumentation used to measure the contact velocity is the displacement sensor which is connected to the solenoid. The method used to control the contact velocity is to control the supply voltage to the motor of the solenoid.

5.1.1 Displacement sensors

The pivot mechanism moves in a curve with a very high speed, it is very difficult to measure speed directly from this system. It is not very difficult to measure the velocity of the solenoid movement and calculate the speed of the pivot mechanism and contact. The displacement transducer uses a filter pattern together with intensity sensitive photo sensors. Details of the displacement transducer control circuit and differential op-amp circuits are shown in Figure 5.1 –5.2. 

Figure 5.1:  Control diagram of displacement transducer

Figure 5.2: Detail of the differential circuit for output signal of displacement transducer

Dr Kesorn Pechrach Weaver: Piezoelectrics in Circuit Breakers: Piezoelectric Instrumentation

Dr Kesorn Pechrach Weaver: Piezoelectrics in Circuit Breakers: Piezoelectric Instrumentation: Piezoelectric Instrumentation The Piezo-ceramic used as the actuator in this paper is Lead Zirconate Titanate (PZT). The...

Piezoelectric Instrumentation

Piezoelectric Instrumentation

The Piezo-ceramic used as the actuator in this paper is Lead Zirconate Titanate (PZT). The actuator is designed in a U-shape, as shown in Figure 4.13. The material is constructed in a sandwich fashion with layers of PZT material. This structure and the assembly in the U-shape arrangement provide maximum forward deflection of 4 mm and maximum reverse deflection 1.5 mm.

The full specification of the material used is provided in Table 4.1.

Electrical performance
Nominal voltage	325 Vdc
Max. forward voltage	500Vdc
Max. reverse voltage	75 Vdc
Physical performance
Nominal deflection per volt	10-6 m.
Max. forward deflection	4 mm.
Max. reverse deflection	1.5 mm.
Time to deflect (min)	1.25 ms
Blocking force	0.2 N
Beam release force (max)	2.5 N
Physical data
Ceramic	Lead, Titanium, trace
Substrate	Alloy 42 (Ni,Fe,Si,Mn)

Table 4.1 Characteristics of piezoelectric

A Laser Triangulation Sensor was used to measure the deflection of the piezoelectric. The sensor has a 0.01µm resolution. The power supply for piezoelectric was used dual step up transformers transform from 230Vac to 360 Vdc via variable resistor. More than 200 data and 12 sets were recorded to study the relationship between supply voltage and deflection of the piezoelectric

Ronsek Ltd 

Piezoelectrics in Circuit Breakers