Mobile Testing Lab

Keep your rotating electrical machines operating properly, minimize repairs and downtime.

Mobile testing lab

KEEP YOUR ROTATING ELECTRICAL MACHINES OPERATING PROPERLY, MINIMIZE REPAIRS AND DOWNTIME.

Our preventive maintenance program allows you to run pre-defined maintenance at specific intervals, so you can catch potential problems early on before they become major issues.

VISUAL INSPECTION THROUGH BORESCOPE AND ACOUSTIC CAMERA

We are equipped with the latest state of the art tools to detect issues and significantly lower costs associated with mechanical bearing issues and partial discharge on electrical equipment:

  • Partial Discharge Detection
  • Pressurized Leak Detection
  • Mechanical Fault Detection

STATOR / ROTOR WINDING SURGE TEST

The surge test directly measures the integrity of the turn insulation in form-wound or random-wound stator windings, as well as in wound induction rotor windings. As envisioned in IEEE 522 and then IEC 60034-15, the test is primarily intended for ensuring the integrity of the turn insulation in individual coils. However, it has seen some applications for testing the turn insulation in both new and in-service complete windings. The surge test does this by applying a relatively high voltage surge between the turns. So missing, damaged or weak turn insulation can be detected.

The surge test is also applicable for testing the DC armature (low impedance) windings.

STATOR WINDING TAN DELTA AND DELTA TAN DELTA MEASUREMENT

The Tan Delta provides a measure of the dielectric losses within the insulation. Certain deterioration processes, such as thermal aging or moisture absorption, will increase these losses. Thus, the trending of the dielectric loss over time is an indication of certain types of insulation problems. The test is relevant for stator windings only and is usually applied only to form-wound stators.The test is also employed by some original equipment manufacturers (OEMs) to determine when the resin in newly manufactured coils, bars, or global VPI stators is cured.

The  Tan   measurement is an indirect way of determining if partial discharges are occurring in a high-voltage stator winding. As PD is a symptom of many high-voltage winding insulation deterioration mechanisms, the tip-up test can indicate if any failure processes are occurring. This measurement is only relevant to form-wound stator coils rated at 2300 V and above. In addition to its use as an off-line maintenance test, the tip-up test is widely used by stator coil and bar manufacturers as a quality control test to ensure proper impregnation by epoxy and polyester during coil/bar manufacture.

STATOR WINDING PARTIAL DISCHARGE MEASUREMENT (OFF-LINE)

The off-line partial discharge measurement is carried out when the motor or generator is out of service, HV-supply cables are disconnected and isolated. Stator winding is then energized using an external “PD-free” high voltage source. Our power source is providing a “PD-free” voltage source up to 20 kV and up to 800 nF. Measurement conditions differ from normal operation, like cold conductors, influence of environmental conditions, etc. The measurement is carried out with a step increase on steps in voltage (20%, 40%, 60%, 80% and 100% on the nominal line to line voltage) and the PD are recorded on each step. The PRPD are acquired for 60s on each step.

The main advantages of this measurement are that it can:

  • Indicate the main cause of the PD
  • Indicate how severe the condition of the stator winding’s insulation
  • Early detection allows intervening partial repair in an early stage and often avoids immediate rewinding

ELECTROMAGNETIC IMPERFECTION TEST

The electromagnetic imperfection test (also known as stray flux measurement, ELCID) is performed to detect stator core interlamination imperfections that can eventually cause overheating and damage to the stator core of motors and generators when in operation. Stator core measurements are performed offline during bigger maintenance shutdowns. They should be performed on a regular basis to evaluate the insulation integrity between the stator core layers of a machine during factory acceptance testing and commissioning, as well as after the machine has been put into service. The test results are compared with previous test results to verify stator condition. The main advantage of this low-flux test is that when stator windings are in place deeper imperfections can be easily detected without further development of the damaged insulation.

ROTOR WINDING RSO TEST (2 AND 4 POLE MACHINES)

It is an off-line test that can be used for detecting shorted turns, ground faults and high resistance connections in synchronous machine rotors. The data obtained from the recurrent surge oscillography (RSO) test can also be used to identify the location of the fault. These test procedures are primarily for round rotors in synchronous turbine generators and motors but can also be applied to salient pole rotors with up to 4 poles. The test can be performed in situ (no need of disassembling) both at standstill and at rated speed.

STATOR WINDING PARTIAL DISCHARGE MEASUREMENT (ON-LINE)

The on-line partial discharge measurement is recording and trending the PD activity for a period of time or permanently. The trend analysis is proven to be the best early warning method for the insulation state of rotating machines. The on-line PD measurement is carried out via preinstalled coupling capacitors.

The main advantages of this measurement are that it can:

  • recording and trending for a period of time
  • indicates the high PD activity by rising an alarm
  • recording the PD activity in different operation conditions, like different load, different temperatures, etc.
TESTS AND MEASURMENTS REFERENCE VALUES
TEST/MEASUREMENT DESCRIPTIONREFERENCELIMIT
 Measurement of the DC-resistance of the stator/rotor windingIEC 69934-2-1, IEE Std. 67 
 Measurement of the stator/rotor winding or coil inductance at 1 kHzSpecific 
Measurement of the insulation resistance, polarization index, and step voltage of the winding and accessories IEC 60204-1, IEC 60204-11 10 kV DC
Function test of accessories and sensorsSpecific 
Stator/rotor winding Surge test IEC 60034-15, IEEE Std. 522 15 kV
Rotor winding voltage drop test IEEE Std. 1665 400 V AC
Rotor winding RSO test IEEE Std. 1665 
Polarity testSpecific 
Stator/rotor winding Hi-pot test IEC 60034-1 20 kV AC, 50 kV DC
Stator winding Tangent Delta measurement IEC 60034-27-3, EN 50209 20 kV 800 nF
Stator winding Partial Discharge measurement (Off-line) IEC 60034-27-1 20 kV 800 nF
Electromagnetic Core Imperfection Detection (ELCID) test CIGRE TB 257 
Shaft voltage measurement IEEE Std. 115