Transformer And Traction Converter Flashcards
How many internal windings does a transformer have and what are they called?
It has 3 :
• Primary - 25,000v AC
• Secondry - 1500v AC
• Tertiary - 240v AC
How is the transformer cooled?
It is cooled by pumped oil which is contained in the transformer.
Also cooled by forced air via the fins around the casing.
Why is there a primary overload valve fitted?
It senses over voltage in the primary winding.
If there is a over voltage then the VCB will open and if you can not reset from the desk the flag is tripped externally on the auxiliary converter the set is a Failure!
What is the function of the secondary overload?
Senses a over voltage in one or both of the secondary windings to the traction converters.
Therefore not allowing traction power to the relevant traction motors.
What is the function of the over temperature relay and what symptoms will you receive in the cab?
Also what will happen to VCB?
Power lost.
Transformer fault in TS and general fault light will illuminate.
Will only regain power when temperature falls below 110c.
Must be reported.
The VCB will remain set to allow the oil pump to still run to cool down the transformer.
There are two secondary windings what voltage do they run at?
There is one for each traction converter at 1500v AC.
The secondary windings have overload relays to stop there from being to much voltage in one or both windings. Where are they located and which vehicle do they relate to?
It can be checked at the auxiliary converter.
Secondary overload 2 : DMS B 65xxx
Secondary overload 1 : DMS A 64xxx
What is the function of the QUALITROL RELIEF VALVE? How would you no it has operated? What happens if it don’t reset?
Operates to vent excess air pressure from the transformer and will also discharge coolant.
There would be a yellow pin coming out the bottom.
The set will be a failure.
What is the function of the BUCHOLZ RELAY? How would you no it has operated? What happens if it don’t reset?
It detects gas or air in the coolant. It prevents damage to the transformer by opening the VCB. It show on the dash by VCB light lit and line light off.
Pan up/reset will have no effect.
If it won’t reset it will be a failure.
What’s the function of the transformer silica gel breather?
Takes the moisture out of the air of the transformer. Ensures only dry air enters transformer.
Describe the function of the traction converter when taking power?
The traction converter distributes power to the traction motors.
Describe the function of the traction converter when braking?
The traction converter supply’s power for regenerative braking at 0-1950v AC depending on what level of brake is applied by the driver. Power to used is sent back to transformer and back to the OLE.
How many traction motors are there and where are they located?
There are 8 in total.
2 on each bogie on the DMS
What will happen if the cooling fan fails on the traction converter?
The traction converter will be lost for both functions power and regen brake.
How does a driver isolate a traction converter and what effect would it have on a single unit?
Isolation switch is operated with a master key. Traction power would lose 50% on a single unit. As all traction motors would be lost on that car and you would lose re gen brake.
