Power Frequency Series Resonant Test System

The generator AC withstａnd voltage test requires the use of power frequency withstａnd voltage, and

the international definition of the power frequency voltage frequency is 45Hz-65Hz; but in many

test occasions, it is required to perform the AC withstａnd voltage test of 50Hz±1Hz on the

generator[1], and The electric capacity of the generator stator winding to ground is relatively

large. Most domestic test units use resonant transformers to test it. However, the resonant

transformer itself is very heavy and often weighs a ton, making field tests very troublesome.

In response to this, in the Power Frequency Series Resonant Test System, the device adopts an

adjustable reactor to adjust the inductance of the reactor to reach the resonance state, or

adjusts the operating frequency of the system to reach the resonance state, and the above two

methods can also be used to reach the resonance state. When the frequency is required for the

test, adjust the frequency of the excitation source to the required frequency, and then adjust the

inductive reactance of the reactor according to the capacitance of the tested product to make the

system resonate and generate high voltage. During the boost process, how The resonance point is

too high. The resonance point can be accurately found by fine-tuning the frequency to ensure a

high Q value, thereby minimizing the capacitance and the volume and weight of the test equipment.

180kVA/5kV/6.5kV/0.4kV Exciting transformer 1 set

300kVA/0.4kV/0.4kV Isolated transformer 1 set

180kW/0.38kV Electric Console 1 set

600kVA/50kV（8～80H） HV adjustable reactors 1 set

600kVA/50kV（10H） Fixed reactors 1set

50 kV Voltage divider 1 set

Sphere gap 1 set

Schematic diagram about equipment wiring

1.Connect the three-phase four-wire power supply A, C and N with the corresponding terminal on the lower side of the console (if the phase sequence is inconsistent with equipment, the console cannot work and start normally, so phase sequence of the power supply needs to be replaced).

2.Connect console to the voltage regulator, wiring from console to exciting transformer, match the terminal one to one, and specialized aviation plug one to one.

3.Set the overcurrent relay

Protect the overcurrent (LV ammeter meter)

according to the overcurrent protection sign on the panel of console .

Generally converted to LV capacity according to 1/Q capacity of tested equipment , calculate the LV current and voltage under the test voltage, and set the overcurrent protection according to 1.5 times of LV current. Then through simulation test to ensure the overcurrent protection action to cut off the current( 120MW turbine, Q value is about 8 – 10) .If the current of tested object is 8A, voltage is 25Kv, the capacity of device should be 200KV, take Q value as 10, and the LV capacity is 3Kva, LV is 400V, LV current is 250A, and the overcurrent protection setting value is 250A

4.Setting over voltage protection

Electronic overvoltage protection setting: 1.1 times of withstａnd voltage value, automatically locked voltage boost once over voltage protection act.

5.Connect measurement meter : HV side of tested object connect with voltage divider (HV meter) to measure the HV voltage .

6.Connect with tested object to make AC withstａnd voltage test

7.Check if all test equipment in good condition before withstａnd voltage test

8.Security arrangement is complete enough for testing .

9.No-load adjustment test to ensure test device is good condition

10.Boost test: Connect with analog load or tested object, step up/step down button , boost 10% -20%, and then adjust the adjustable reactor .Inductance button When the HV measurement meter indicates maximum value, it means find out resonance point (The voltage reach maxmum value at resonant point),then boost or step-down voltage step by step to test voltage, and the voltage will step-down automaticaly when timing is up .

11.Verify overcurrent protection : Connect with simulated load, monitor and step-up voltage on console, and monitor currrent at the same time , (LV current meter)

When current reach protection setting value , protection will act , trip and cut off power supply.

12.Verify overvoltage protection : Connect with simulated load, monitor and display on console(or monitor from HV mter of voltage divider),

When voltage reach protection setting value, overvoltage protection act, Alarm light is on, cut off the power supply and back to zero automatically .

13.Connect with tested object, adjust the resonance . For resonance in parallel , adjust it until the value on current meter reach minimum .

For resonance in parallel, available to adjust resonance at any time when under 80% test voltage.

Begin to adjust resonance while rated input voltage of exciting transfromer is 10%-20% (LV voltage meter)

Until the the maximun output voltage is the resonane, and not allowed to adjust air gap, to avoid over voltage (Recommend resonance in paralle for test electric generator)

14.Boost to withstａnd voltage value( due to the voltage increase at Q times, a point - boosting is necessary). If there is no abnormal phenomenon in 1 minute , voltage regulator will step-down to zero automatically .During the test, the relevant personnel should strengthen the monitoring of tested equipment. In case of abnormal phenomenon, or overcurrent protection action, should decrease voltage and cut off the power supply quickly .

15.Switch-off: reduce air gap to zero, close all switches, test complete

16.For same unit, , test in sepearate phase, once the resonance point is adjusted, no need to adjust the air gap when make withstａnd voltage test for other phase, can directly boost to the test voltage

17.After finish test, can only discconect the wiring after tested object is completely discharged.

18.Tested object

Ac withstａnd voltage test 18kV/300MW hydrogenerator, the capacitance is 1.6uF when single-phase to ground , and the maximum test voltagenot exceed 39kV.

Relationship List in Test

Product service process

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1. Dear customers, no matter what you need, as long as you contact us, we will do the rest!

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5. The engineer will explain to you the working principle and test operation steps of the product in detail.

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2.Upon receipt of the client's request for after-sales service,we promises to provide solutions within 48 hours.

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4.The product can be repaired free of charge for one year and maintained for life.

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