Stator Roebel Bars
Electrical Routine Test
The electrical routine testing at different stages is performed with guidelines of IEEE/IEC/IS international standards.
The individual bars testing and Stator testing after winding & connection is shall perform as per our below standard norms
| S.no | Stage of testing | Electrical Test | Resin Rich Bars | VPI Bars |
1 | Test on Individual bars | Tan delta and capacitance measurement with guard electrodes | The tan delta measurement carried out from 0.2 VL to 1.2 VL insteps of 0.2 VL | The tan delta measurement carried out from 0.2 VL to 1.2 VL insteps of 0.2 VL |
| Surface Resistance Measurement | Surface resistance measurement shall be carried out on slot portion conducting tape | Surface resistance measurement shall be carried out on slot portion conducting tape | ||
| Insulation resistance test | IR for 1 minute at specified Voltage | IR for 1 minute at specified Voltage | ||
| Ac high voltage test | 1.3 X ( 2 X VL + 1 ) for 1 minute | 3 x VL for 1 minute | ||
| Insulation resistance test | IR for 1 minute at specified Voltage | IR for 1 minute at specified Voltage | ||
2 | Test before stator connection (after bars insertion in wound stator) | Insulation resistance test | IR at 1 minute and 10 minute | IR at 1 minute and 10 minute |
| Ac high voltage test | 1.2 X ( 2 X VL + 1 ) | 1.3 X ( 2 X VL + 1 ) for 1 minute | ||
| Insulation resistance | IR at 1 minute | IR at 1 minute | ||
| RTD’s high voltage a.c | At 1.5 kv for 5 seconds | At 1.5 kv for 5 seconds | ||
| RTD’s resistance | Record the resistance of all RTD’s | Record the resistance of all RTD’s | ||
3 | Test after stator connection with cables | Winding resistance | Resistance per phases at room temperature | Resistance per phases at room temperature |
| Insulation resistance test | IR at 1 minute and 10 minute | IR at 1 minute and 10 minute | ||
| Ac high voltage test | 1.1 X ( 2 X VL + 1 ) | 1.2 X ( 2 X VL + 1 ) | ||
| Insulation resistance | IR at 1 minute | IR at 1 minute | ||
| Tan delta and capacitance measurement | The tan delta measurement carried out from 0.2 VL to 1.2 VL insteps of 0.2 VL | The tan delta measurement carried out from 0.2 VL to 1.2 VL insteps of 0.2 VL | ||
| RTD’s resistance | Record the resistance of all RTD’s | Record the resistance of all RTD’s |
Where VL – The Rated line voltage of the stator bars.
Acceptance Criteria:
- Surface Resistance – The surface resistance of coils/bars should be 500 ohms to 5000 ohms/square
- AC HV test – Rivera Standard Norms and IEC 60034 & BS 499-5000 – Should not be failure in slot portion at specified voltage for duration of 1 minute
- Insulation Resistance (IR) and Polarization Index (PI) – IEEE 43 -2000 – The minimum value of IR 1 minute is 100 MΩ and PI 10/1minute is 2.5
- Tan delta test – IEEE 286 -2000 & IEC 60034-27
- At 0.2 * Un Dissipation factor should < 2 %
- Tan delta dissipation factor per 0.2 * Un should < 0.5%
- Dissipation factor tip-up between 0.6 * Un and 0.2 * Un should < 0.5 %
Electrical type test and testing standards
A voltage of 2 Un + 1 KV shall be applied for 1 minute between coil terminals and earth. The applied voltage shall then be increased at the rate of 1 kV/s up to 2 * (2*VL+1) kV, and then immediately be reduced at the rate of at least 1 kV/s to zero. There shall be no voltage breakdown during this sequence.
There shall be no voltage breakdown at 1.5 * VL + 1 for 30 seconds duration, 10% of total coils/bars.
The slot portion of the coils and bars from high voltage withstand test cut into equal lengths, then microscopic investigation and measuring of insulation thickness shall be performed.
The coils/bars temperature rise from 40°C to 150° C and cooling from 150°C to 40°C for 500 cycles. During TCT tapping test, Tan delta test and PD measurements shall be repeated after 50,100,250 and 500 cycles.
The Voltage endurance test shall be performed on the coils/bars with schedule B.
| Coils/bars line voltage | 6.6 kV | 11 kV | 13.2 kV | 13.8 kV | 15.75 kV |
| Test voltage in Schedule A (400Hours at 120°C) | 14.3 kV | 23.87 kV | 28.64 kV | 29.94 kV | 34.177 kV |
| Test Voltage in Schedule B (200Hours at 120°C) | 16.69 kV | 27.83 kV | 33.39 kV | 34.91 kV | 39.84 kV |
The standards used for testing are
- AC High Voltage Withstand test : IEC 60034-15
- Insulation resistance measurement: IEEE 43-2000
- Tan delta and capacitance measurement: IEEE286-2000 and IEC 60034-27-3
- Partial discharge measurement: IEEE 1434-2014
- Thermal cycling test: IEEE 1310-2012
- Voltage endurance test: IEEE 1043-1996 and IEEE 1553