Transformers #3370472

Dimmerstat is registered trademark of AE for continuously variable voltage auto-transformer. It is the most effective device for step less, break less & continuous control of AC voltage & therefore for various parameters, dependent on AC voltage.
The basic Dimmerstat is meant for operation from a nominal input voltage of 240V AC & can give output voltage anywhere between 0 to 240V or 0 to 270VAC by simple transformer action. Three such Dimmerstat connected electrically in star and mechanically in tandem, become suitable for operation from a nominal input voltage of 415V 3Ph AC and can give output anywhere between 0 to 415V or 0 to 470V.
Resin moulded Dimmerstat is basically a variable Voltage Auto-Transformer which is partly or fully Moulded in Reinforced Polyester Resin. This has adjustable spindles which allow easy assembling of flush, table or Motorized Type in single or three phase models. These models are designed up to 120% continuous load.

Features

• Simple, rugged construction.
• Coils made from high grade CRGO Silicon Steel & 99.9% pure Electrolytic copper.
• Output voltage variation is smooth, continuous, break less & linearly proportional to angular rotation.
• High efficiency.
• Negligible waveform & power factor distortion.
• Excellent short time overloads capacity.
• Remote operation possible by motorization.
• Wide range of current ratings.
• High quality carbon brush used for current collection.

These Rectifier units are suitable for all electro deposition processes within their rating. The widest applications in the field require maximum voltage of 8V, 12V and 20V D.C. at various current capacities as per requirement. A range of current ratings from 100 amps to 10000 amps is covered in our regular manufacture. Our standard sizes are listed in the price list issued separately.

Brief Specification

• Input Voltage: 360 to 440V A.C. 3 Phase 50 Hz 4 Wire
• Output Voltage: Continuously variable from zero to the full rated D.C. voltage
• Output Current: From zero to Rated maximum D.C. Current
• Efficiency: Above 80%
• Temperature Rise: Less than 45°C above ambient at the top of the oil

Any Double Wound Transformer is internally an isolation transformer as the primary and secondary are isolated from one another through insulation. However, modern machines and systems need a truly isolated, clean and stable power requirement. This is ensured by an Ultra Isolation Transformer (UIT), it provides for total electrical and electrostatic isolation with most effective screening of spikes, surges and transients, further it gives a true isolated local neutral and dedicated earth which is very essential for modern machines. Ultra isolation Transformer attenuates common mode noise and transverse mode noise and provides for noise or interference free power. In principle, UIT only transfers 50 Hz. Power by transformers action through mutual inductance. It prevents transfer of RF and HF disturbances with extensive insulation between primary and secondary. The insulation levels withstands HV breakdown strength of 2.5 KV and gives a DC Galvanic isolation of above 1000 megohms.

Following are main factors for selecting Voltage Transformer.

• Service Voltage:System Voltage in which V.T is to be installed e.g. 11kv, 22kv, 33kv etc.
• Installation:Whether OUTDOOR or INDOOR
• Atmospheric Conditions:Such as condition of Pollution, Altitude, Ambient Temperature etc.
• Insulation Level:If insulation level other than associated with service voltage is required, it should be specifically mentioned.
• Rated Primary Voltage:Rated primary voltage is generally rated system voltage for unearthed type V.Ts. and rated system voltage divided by square root of three for earthed type V.Ts. The V.Ts. can be manufactured suitable for more than one system voltage. In such cases, different primary voltages required may be indicated.
• Rated Secondary Voltage:Standard Values of Secondary voltages are 110v or 110v/13 depending on application of the secondary winding. V.Ts. with different secondary voltages other than those mentioned above can be manufactured and supplied.
• Voltage Factor:All V.Ts, are manufactured suitable for continuous voltage factor of 1.2. As per I.S. / L.E.C. Specifications, short time voltage factor is different for different earthing systems. Therefore appropriate system earthing conditions may be specified.
• Number of secondary windings. Their burdens & accuracy classes:Number of secondary windings, their burdens and accuracy classes are selected on the basis of application. Two types of classes are available, one for metering and other for protection. Unlike current transformers, accuracy of one winding is influenced by loading of other winding. Due to this reason burden of each winding should be correctly mentioned. Accuracy of V.T. is guaranteed at the secondary terminals of the V.T. The impedance of cable connecting secondary terminal to load (Relay or Meter) offers series drop in output voltage. This causes additional errors in secondary winding at the measuring end of cable and is proportional to the load on the secondary. Therefore, it is advisable to select separate metering and protection winding. Alternatively, single winding can be used for metering and protection if separate cables are used for connections. (Cable of 4 sq. mm. cross section offer 2% voltage drop at 100 metres distance will 100 VA burden for secondary voltage of 110v/A).

Since, we are famous suppliers of Low Tension Power Transformer, buyers can place order with us and quote their prices. As a customer-focused firm, we strive hard to delight them with high quality range of products that are the perfect outcome of premium raw material and modern work methods.

No of Phase

• Single Phase
• Three Phase
• Three Phase to single Phase
• Three Phase to Two Phase (Scott)

Type of Transformer

• Double wound Transformer
• Auto wound Transformer

Type of cooling

• Natural Air cooled
• Natural Oil cooled

AUTOMATIC ELECTRIC LTD. introduced their indigenously developed INSTRUMENT TRANSFORMERS in the year 1968. Since then ‘AE’ are one of the leading Manufacturers in the Country for quality instrument Transformers. ‘AE’ manufactures OUTDOOR OIL COOLED VOLTAGE TRANSFORMERS ranging from 11kv to 220kv. The Modern Plant situated at Ambernath is equipped with full range of testing equipments, plant & machinery to manufacture INSTRUMENT TRANSFORMERS. ‘AE’ have supplied thousands of these transformers to almost all the STATE ELECTRICITY BOARDS and utilities in the Country. These INSTRUMENT TRANSFORMERS are working satisfactorily under different service conditions at the sites. ‘AE’ are also EXPORTING transformers. The instrument transformers are fully type tested in accordance with latest I.S. /I.E.C. Specifications.

APPLICATION :  Direct measurement of voltage in High Voltage System is not possible because of insulation problem of measuring instruments. It is also not possible to use direct voltage for the system protection purpose due to its high value and high insulation problem of protective relays. Therefore, voltage transformers are used to step-down the high system voltage to low standard value accurately in proportion to their ratio.

AUTOMATIC ELECTRIC LTD. introduced their indigenously developed INSTRUMENT TRANSFORMERS in the year 1968. Since then ‘AE’ are one of the leading Manufacturers in the Country for quality instrument Transformers. ‘AE’ manufactures OUTDOOR OIL COOLED VOLTAGE TRANSFORMERS ranging from 11kv to 220kv. The Modern Plant situated at Ambernath is equipped with full range of testing equipments, plant & machinery to manufacture INSTRUMENT TRANSFORMERS. ‘AE’ have supplied thousands of these transformers to almost all the STATE ELECTRICITY BOARDS and utilities in the Country. These INSTRUMENT TRANSFORMERS are working satisfactorily under different service conditions at the sites. ‘AE’ are also EXPORTING transformers. The instrument transformers are fully type tested in accordance with latest I.S. /I.E.C. Specifications.

APPLICATION :Direct measurement of voltage in High Voltage System is not possible because of insulation problem of measuring instruments. It is also not possible to use direct voltage for the system protection purpose due to its high value and high insulation problem of protective relays. Therefore, voltage transformers are used to step-down the high system voltage to low standard value accurately in proportion to their ratio.

1.Service Voltage :System Voltage is which CT is to be installed e.g. 11 kV, 22 kV, 33 kV. etc.

2.Installation :Whether OUTDOOR or INDOOR

3.Atmospheric Conditions :Such as condition of Pollution, Altitude Ambient Temperature etc.

4.Insulation Level :If insulation level other than associated with service voltage is required, it should be specifically mentioned

5.Rated primary current :Specify rated primary current / currents (if required more than one value) Also indicate if different primary current is required for different cores.

6.Continuous Primary current :Max. primary current that can be withstood continuously by current transformer e.g. 120% of primary current.

7.Rated secondary current :Whether 1 Amp or 5 Amps

8.Short Time Current & its Duration :Specify fault current of the system in which CT is to be installed along with its duration. It is most important to specify realistic value of S.T.C. as at lower primary current, higher S.T.C. value necessitates bulky & costlier design. Also specify dynamic current if other than 2.5 times S.T.C. is required.

9.No. of cores Their Burdens Accuracy :Basis of application, No. of cores, their burdens and accuracy class should be specified. It is advisable to specify minimum required Burden for metering core as unnecessary high burden will necessitate for bulky and costlier design. Specified accuracy is guaranteed for 100% to 25% of rated burden only. Current transformer offers minimum error if 75% to 60% burden is connected to secondary. Therefore, ideally rated burden higher than 1.5 time actual burden should be specified.
Also, it is important to specify correct burden in context of Instrument Security Factor (I.S.F.) The I.S.F. indicates the over current as multiple of rated current at which the metering core will saturate, thus limiting the secondary current flowing through meter and protect it from damage. If actual burden connected is half of the rated burden, the actual I.S.F. will increase two-fold of its rated value.

10. Knee point voltage, Secondary resistance and excitation current :For differential protection. R.E.F. Protection, Bus Bar Protection. C.T. with accuracy class PS is required. The Knee Point Voltage. Secondary resistance and excitation current should be specified for this core. It is always better to specify Formula for Knee Point Voltage related to relay used for the protection. This will help designerto optimise the design.

AE- 65(45) Series

• Model 65/14, 65/21 available in Accuracy Class 0.5, 1 & Class 3
• Orders for different ranges of CT’s are accepted on request.
• 5A & 1A Secondary available.
• For all transformers DIN RAIL plate can be supplied (as per DIN EN 50022) on request.