The transformer ratio is one of the most important parameters of transformer, it usually references the winding ratio between input coils and output coils. The transformer ratio testing is an important way to judges whether the transformer accords with the design parameters or not. The basic method is according to measures the ratio between input voltage and output voltage of transformer to identify the changes.
There are some main ways to do the test of transformer ratio:
1.Manual measurement method.
This method adapts to some small transformer. Firstly, put the multimeter and voltmeter into the low pressure side and high pressure side, meanwhile, records all of the voltage value respectively. Then, changes the connection status of coils of high pressure side, and measures the voltage value of low pressure side again. Last, according to the ratio between low pressure side and high pressure side to decide turns ratio.
2.Automatic measurement method.
This method adapts to some big transformer, it usually uses professional measurement instruments, such as turns ratio table, insulation resistance tester etc. Automatic measurement through gathers data automatically and computes, it has the two merits of high accuracy and high efficiency.
3.Phase difference method.
This method uses the voltage value between low pressure side and high pressure side of transformer and the phase difference of current to testing turns ratio. Firstly, we use multimeter and oscillograph to measure the voltage value between low pressure side and high pressure side, the current value and the phase difference. Then according to the phase difference between current and voltage to compute turns ratio.
4.Comparative method.
This method throughs comparing the output voltage value between the two transformers to test turns ratio. Firstly, put the standard transformer and to be tested transformer into the same AC power at the same time, and then testing their output voltage ratio to get the turns ratio of to be tested.
5.Electronic bridge method.
This method uses electronic bridge to measure the turns ratio. Firstly, put the known and standard turns ratio into the electronic bridge internet, and then adjusting electronic bridge to let the balanced hands get into the central location. Then, put the to be tested transformer into the electronic internet and adjusting the bridge again and recording the bridge ratio when balanced, Lastly, compute the to be tested transformer's turns ratio according to bridge ratio.
All of these methods have their own characteristic, and these are applicable to different scenarios and turns ratio demands. People need to choose suitable testing methods and make sure the accuracy and safety when testing.