ACCESSORIES
Standard accessories
• N. 4 bidirectional wheels
• N. 2 grounding terminals
• N. 1 identification plate
• N. 2 or 4 lifting lugs (according to rated power)
• N. 4 connections for haulage
• No load tap changer
• Oil level indicator without contacts (for conservator type only)
• Thermometric pocket
ACCESSORIES ON REQUEST
Many accessories are available for the TTO Oil transformers for safety, protection, measuring or just to comply with the customer’s specification. A list of the most commonly used is given below.
For other needs, please contact our technical or commercial department.
Two-contacts dial thermometer A cheap and reliable device to obtain the oil local temperature in the highest layers and control (through the two contacts) the alarm and trip relays in the control room.
Buchholz Relay
(for transformers with oil conservator only)
This device is interpositioned inside the connection pipe between the lid and the conservator. It intercepts and collects possible gas bubbles coming from the active part (indicating a localized overheating caused by a hot spot or discharge) and gives an alarm signal when reaching a specific quantity. In case of serious breakdowns (oil wave
toward the oil conservator) it gives a trip signal.
Dryer
(for transformers with oil conservator only)
Filters air entering in the conservator eliminating humidity. In this way the air entering in contact with the oil inside the conservator is dryed, preventing the oil from absorbing the humidity and worsening its dielectric properties.
For proper performance, it should be inspected and regenerated periodically.
Level indicator with contact/s
(for transformers with oil conservator only)
In addition to the visual indication, it gives a signal when the oil reaches its minimum/maximum level.
Overpressure valve
(recommended for hermetic transformers)
In case of an elevated internal overpressure (caused by a breakdown) the valve releases internal pressure outside preventing or limiting the mechanical damages caused to the tank, which may cause oil leakages.
The version with electric contacts for release signal is available on request.
Integrated safety system
(recommended for hermetic transformers)
Combines 3 signals/protections in one single device: oil level, internal overpressure, oil temperature.
Plug-in connections MV side
(fixed part only)
Line connections MV side are designed to be connected to medium voltage cables with plug terminal.
The plug connection allows a very rapid connection of the cable to the transformer and can be touched also when the transformer is under voltage.
The transformer can be left without the segregation cell by properly protecting the LV side as well. In any case, pls. follow current local rules for the safety of
installations under voltage. Always notify the type of rapid connection desired.
Antivibration supports
The standard version includes special rubber supports supplied loose for the customer to position under the wheels of the transformer. They greatly reduce the
vibrations transmitted to the structure and therefore the noise and possible structural resonances.
Antivibration supports designed on the customer’s specification may be designed and supplied for special applications.
MV double voltage
MV winding has been designed to work on two different voltage levels (e.g. 10- 20 kV) and the selection is made through the commutator with control on the lid.
Auxiliary service box, protected model
Centralizes the possibile auxiliary services and protects the terminal board.
Electrostatic screen between primary and secondary
It greatly reduces coupling capacity between MV and LV winding. This drastically reduces the overvoltages transferred from MV to LV which in certain cases may damage any sensitive loads.
Spark gap rods