An Excitation Capacitor is a three terminal device that’s used as part of a 3 period Asynchronous Generator System. Such a Generator includes three built-in parts, namely a Stator (a type of Transformer), a Rotor (a driven shaft with magnetic properties) and a number of Excitation chip tantalum capacitors SMD.
The Excitation Capacitor consists of three individual chip tantalum capacitors SMD which are joined in such a way that two are in series with a third capacitor in parallel. Due to this arrangement, when measuring the capacitance between each terminal, the value that is measured will always be 50% higher than the stated Capacitance of each individual part. For example, a 50uF Excitation Capacitor will read 75uF when there is a Capacitance Meter joined between each pair of terminals.
It is especially significant they are completely discharged before Testing Excitation chip tantalum capacitors SMD. A completely charged Excitation Capacitor would ordinarily have numerous Volts applied to it, and are capable of keeping an enormous amount of Energy. This energy sits there for a very long period of time, only looking for a spot to go (a discharge route). Failing to safely discharge these chip tantalum capacitors SMD through a suitable Bleed Resistor can cause an electric shock hazard, or cause damage to your own Test Equipment. For your security, please do not blow off this Warning!
There are three common approaches of testing Excitation chip tantalum capacitors SMD on www.sh-jinpei.com. They are:
1. What I will call, ‘The Poor Mans’ method. All which will be ascertained is whether the chip tantalum capacitors SMD are capable of taking charge, by performing this type of Functional Test. It is not a definitive Test method, but is an exceptionally common practice for evaluating functionality of these parts. Assuming that you are using a DVM.
The DVM is for taking a Resistance measurement set up. Apply the Test Leads to each Capacitor. The DVM will show a low Ohms reading (towards Zero Ohms). After a little period of time, the Resistance reading will increase. Here is the normal characteristic of a charging Capacitor. Perform this test for all three chip tantalum capacitors SMD. When you do this, what you are seeing is the Capacitor taking charge from the internal battery. This process relies on the fact that when a voltage is first applied to your Capacitor (at time = 0), a Capacitor will seem as a short circuit. Consequently, the zero Ohm reading. As time goes on (constrained by the formula: T=RC), the Voltage that is applied will be eventually charged to by the Capacitor.
2.Using an ESR (Equivalent Series Resistance) Meter or ESR Examiner, apply the Evaluation Leads to each Capacitor. If using an ESR Meter, support the ESR is low in relationship to Capacitor’s kind and value being analyzed. This can be usually correlated from a lookup graph. For a good Capacitor the ESR will generally be less than 3 Ohms (and preferably less than 1 Ohm). If using an ESR Tester, a Microprocessor / Microcontroller reveals the status of the component (Suspect, or Good, Poor), thus simplifying Fault Analysis. Capacitor ESR measurements demonstrate the internal Resistance of the Capacitor using an AC Test method.
3. Using a Capacitance Meter, apply the Evaluation Leads to each Capacitor. Verify the chip tantalum capacitors SMD value is 50% greater than the chosen Capacitance for each individual Capacitor. This Test Method will affirm the Capacitance rating of each component (within the tolerance limits of the component).