AS NZS 60214.1:2020 pdf free.Tap-changers Part 1: Performance requirements and test methods (IEC 60214-1:2014 (ED.2.0) MOD).
5.1.2 Compartments for diverter and selector switches
The liquid filled compartments for diverter and selector switches shall be liquid-tight. The gas filled compartments for diverter and selector switches shall be gas-tight. Where appropriate, pressure and vacuum withstand values shall be declared by the manufacturer.
If the insulating liquid is to be supervised by dissolved and free gases analysis (DGA), the liquid filled compartment of the diverter or selector switch should be provided with a liquid conservator which has a liquid and gas-tight barrier. In case of vacuum type OLTCs this matter should be discussed between transformer manufacturer and customer
5.1.3 Liquid-level gauges and gas monitoring devices
Liquid compartments for diverter or selector switches with integral expansion volume or separate conservators for these compartments, when fitted, shall be provided with liquid-level gauges.
Gas compartments for diverter or selector switches shall be provided with gas monitoring devices.
5.1.4 Safety requirements for protection against internal failure
5.1.4.1 General
In order to reduce the consequences resulting from an internal failure within the diverter or selector switch compartment, a protective device shall be fitted. The protective device shall have a function to detect a failure arc or a failure mode that finally will lead to a failure arc.
It is up to the manufacturer to recommend a protection device for the selected OLTC. At least one protective device shall be fitted.
The most common types of protection devices for liquid immersed OLTC are described below.
The tap selector compartments of compartment type on-load tap-changers are usually piped to the main transformer buchholz relay. Consideration should also be given to fitting a separate buchholz relay between the tap selector compartment and the conservator.
NOTE For those types of on-load tap-changers that do not create an arc and are installed in sealed
compartments, other protective devices can be used.
5.1.4.2 Liquid-flow controlled relay
The liquid-flow controlled relay, installed in the pipe between the top of the diverter or selector switch and the liquid conservator, shall respond at a predetermined liquid flow and enable the transformer to be tripped.
5.1.4.3 Overpressure relay
The overpressure relay shall respond in the event of the pressure in the diverter or selector switch compartment exceeding a predetermined value, and enable the transformer to be tripped.
5.1.4.4 Pressure relief device
The pressure relief device shall open when a predetermined pressure is exceeded and its opening shall protect the diverter or selector switch compartment.
Where a pressure relief device is the sole protection, it shall also be arranged with contacts to enable the transformer to be tripped.AS NZS 60214.1 pdf download.