MEDIUM-VOLTAGE MEASURING VOLTAGE TRANSFORMERS USER MANUAL F.T.M. S. r. l. Fabbrica trasformatori di misura Via Po, 3 20090 Opera MI - Italy Tel : +39 (0)2 576814 Fax : +39 (0)2 57605296 E-mail: info@ftmsrl.it Website: www.ftmsrl.it MOD.PRG M042-31.05.2007 1 of 9
CONTENTS 1 INTRODUCTION 2 CHOICE OF DEVICES 2.1 SYSTEM SPECIFICATIONS 2.2 ENVIRONMENTAL CONDITIONS 2.3 SAFETY DISTANCES 3 TRANSPORT 4 STORAGE 5 INSTALLATION 5.1 MECHANICAL ASSEMBLY 5.2 CONDENSATION PHENOMENA 5.3 CONNECTIONS TO THE MAIN CIRCUITS 5.4 GROUND CONNECTIONS 5.5 SEALING THE SECONDARY TERMINALS 6 COMMISSIONING 7 MAINTENANCE 8 STAFF TRAINING 9 TECHNICAL SPECIFICATIONS MOD.PRG M042-31.05.2007 2 of 9
1. INTRODUCTION This manual provides all the information needed to safely operate medium voltage measuring transformers (VTs) suitable for installation and use in medium voltage systems (from 7.2 kv to 36 kv), and IEC 60044-2 compliant. 2. CHOICE OF DEVICES Devices must be chosen so as to meet all the electrical parameters of the system in which they will be installed, paying particular attention to the following: 2.1 SYSTEM SPECIFICATIONS Type of connection to two primary poles to one primary pole Power grid s operating voltage TYPE Operating voltage TYPE Operating voltage 7 Up to 7.2 kv 7 Up to 7.2 kv 12 From 7.2 kv to 12 kv 12 From 7.2 kv to 12 kv 17 From 7.2 kv to 17.5 kv 17 From 7.2 kv to 17.5 kv 24 From 7.2 kv to 24 kv 24 From 7.2 kv to 24 kv 36 From 7.2 kv to 36 kv Rated primary voltage TYPE Maximum rated Maximum rated TYPE primary voltage primary voltage 7 6000 V 7 6000: 3 V 12 12000 V 12 12000: 3 V 17 15000 V 17 15000: 3 V 24 20000 V 24 20000: 3 V 36 30000: 3 V MOD.PRG M042-31.05.2007 3 of 9
Rated secondary voltage 100-110 (V) 100: 3-110: 3-100:3 110:3 ( V ) Rated voltage factor and time 1.2 continuous 1.9 / 30 sec or 8 h Frequency 50 60 Hz Type of use measure or protection All transformer series comply with the product s standards. 2.2 ENVIRONMENTAL CONDITIONS Transformers may be subjected to the following environmental conditions, which need to be carefully taken into account: Temperature All transformer series: from -5 C to +40 C Insulation class E Altitude All transformer series: up to 1000 m a.s.l. Humidity All transformer series: o The mean relative humidity, measured over 24h, must not exceed 95%. o The mean steam pressure, measured over 24h, must not exceed 2.2 kpa. o The mean relative humidity per month must not exceed 90%. o The mean steam pressure per month must not exceed 1.8 kpa. Installation All transformer series: indoor installation Pollution levels All transformer series: installation is possible even in tropical climates MOD.PRG M042-31.05.2007 4 of 9
Corrosive agents To be reported if present Dust and deposits To be reported if present 2.3 SAFETY DISTANCES Safety distances to be complied with in VT installation are as provided by the standards on medium tension insulated power systems. 3. TRASPORT Transformers will be suitably packaged for transport according to the type of product and transport, or to the modality agreed on with the customer. On reception of the device, users are kindly asked to inspect it carefully to ensure the product is undamaged. 4. STORAGE Devices must be stored in clean and dry areas, between -20 C and +70 C (except as otherwise specified). Packaged units may be stacked one on top of another if allowed by and in conformity with the packaging s technical specifications. 5. INSTALLATION All installation operations must be carried out in compliance with all existing accident prevention measures and the following instructions: 5.1 MECHANICAL ASSEMBLY Before tightening, please ensure that the surfaces connecting the conductors and the transformer s primary and secondary terminals are clean and in good conditions. Also ensure that the connections do not cause abnormal mechanical stress to the devices terminals. The maximum and minimum tightening torques of the screw threads to be used for connection to the primary and secondary terminals are as follows: Terminals Screw thread Maximum torque Minimum torque Nm Nm M10 20 10 M6 5 3 Finally, check that no electrical insulation distance was altered during the connecting operation. MOD.PRG M042-31.05.2007 5 of 9
5.2 CONDENSATION PHENOMENA In order for the transformer to withstand the effects of high humidity and condensation, it is advisable to ventilate and heat the installation switchboard, or to apply dehumidifying devices to it. 5.3 CONNECTIONS TO THE MAIN CIRCUITS The primary and secondary connections must be checked to ensure they are compatible with the wiring diagram and the symbols present on the transformers. The graphics printed on the transformers, showing how to connect them correctly, is as follows: Single primary ratio VT with a secondary winding and phase-to-phase connection Single primary ratio VT with a secondary winding and phase-to-ground connection Single primary ratio VT with two secondary windings B/b pole phase-to-phase N/n pole phase-to-ground Single primary ratio VT with two secondary windings, one for measuring, one for residual voltage and phase-to-ground connection Ex.100: 3 Ex. 100: 3 MOD.PRG M042-31.05.2007 6 of 9
Triple primary ratio VT with secondary commutation with a secondary winding B/b pole phase-to-phase N/n pole phase-to-ground Double primary ratio VT with secondary commutation with two secondary windings B/b pole phase-to-phase N/n pole phase-to-ground The correct connections to obtain the different primary burdens are as follows: example: 3000-6000-9000/100 V-V-V/V lowest primary ratio 3000/100 V/V connect to the secondary terminals: a1-b lowest primary ratio 6000/100 V/V connect to the secondary terminals: a2-b highest primary ratio 9000/100 V/V connect to the secondary terminals: a3-b The correct connections to obtain the different primary and secondary burdens are as follows: example: 3000-6000-/100-100V-V-V/V-V lowest primary ratio 3000/100-100 V/V first and second windings connect to the secondary terminals: 1a1-1b/ 2a1-2b highest primary ratio 6000/100-100 V/V first and second windings connect to the secondary terminals: 1a2-1b/ 2a2-2b Please pay maximum attention to the conditions of the VTs secondary circuits, which must be connected to the burden or left open at all times. 5.4 GROUND CONNECTIONS The support plates, one terminal per secondary winding and the N primary terminal of phase-ground TVs must be connected to the ground. MOD.PRG M042-31.05.2007 7 of 9
5.5 SEALING THE SECONDARY TERMINALS All transformers are provided with a thermoplastic cap and fixing screws to protect and seal the secondary clamps. 6. COMMISSIONING To guarantee staff and device safety, please make sure, by checking the specifications on the label, that the system s electrical parameters do not exceed the transformer s nominal parameters. The data reported on the identification label are as follows: 1. Series / Type 2 Code This is an 8-figure code, in which the first two figures represent the manufacturing year. 3 Insulation reference voltage / Power frequency withstand voltage / Impulse withstand voltage Expressed in kv. 7.2/20/60-12/28/75 17.5/38/95 24/50/125 36/70/170 (IEC standard-compliant values) 4 Rated heating capacity Expressed in VA 5 Rated voltage factor and time 6 Frequency Expressed in Hz 7 Product s reference standards. 8 Rated transformation ratio. Rated primary voltage, V / Rated secondary voltage, V 9 Burden applied to the secondary terminals to which the accuracy class refers. Expressed in VA 10 Accuracy class 11 terminals symbols MOD.PRG M042-31.05.2007 8 of 9
7. MAINTENANCE Before carrying out any operation, make sure that the VTs are not connected to the power grid or powered in any way. Check the tightening of the primary and secondary connections. Ensure that the insulating resin surface shows no signs of deterioration such as carbonisation or cracks. Periodically remove any dust or other deposits that may accumulate on the transformers surfaces. Avoid using solvents. 8. STAFF TRAINING All installation, commissioning and maintenance operations must be carried out by trained staff. Staff need to be trained in order for them to operate competently within the field. 9. TECHNICAL SPECIFICATIONS For further information on the field of application and technical definitions, please refer to the product s standard: IEC 60044-2 The products technical datasheets are available online at: www.ftmsrl.it In accordance with the existing law, F.T.M. S.r.l. expressly prohibits any reproduction, retransmission, republication, or other use of all or part of this document without prior authorisation. MOD.PRG M042-31.05.2007 9 of 9