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The electrical safety of student formula racing cars has to be tested before start. The bonding resistance between conducting metal parts shall be not more than 0.3 ohms by testing with 1 A current. The insulation resistance is tested as well. It should be at least 0.3 mega ohms with 500 V testing voltage. The testing without special instrument is time consuming and needs quite a lot of work, as the measurement circuits consist of power supplies, amper- and voltmeters. The meters must be read simultaneously, the results have to be noted and the values calculated by hand.

Being on competitions in Germany, the team members saw, how easily and fast the German colleagues perform the safety measurements by using the measuring instrument Metrahit 27I of Gossen-Metrawatt. The Estonian team decided to have the same measuring instrument for saving the valuable time in competitions. The company Gossen-Metrawatt found a possibility to comply the application of Mr Martin Saar from the Estonian Student Formula to sponsor the team with Metrahit 27I. The product has been sent to Energiatehnika Llt, who is representative of Gossen-Metrawatt in Estonia, to be handed over to the Student Formula team.

The delivery ceremony of the sponsored measuring instrument to team member Mr Martin Saar took place on January the 4th on Rapla carting track. The fast electrical safety tests have been performed to the student formula car. All requested values have been within the permitted limits and the next pilot proceed with the training. Additionally to the safety measurements, the instrument can be used for testing the electrical cables and connections to achieve the maximum possible traction power of the vehicle.

Fig. 1. CEO of Energiatehnika Dr. Juri Joller hands over the measuring instrument Metrahit 27I to the Student Formula team member Riho Koop, B.Sc. responsible for electrical wiring.

Shortly about Metrahit 27I

The combined measuring instrument Metrahit 27I comprises insulation tester, milliohm meter, multimeter and data logger. The instrument has been developed for maintenance and repair of electrical systems of airplanes and helicopters, but suits well for many other applications.

Fig. 2. Combined measuring instrument Metrahit 27I

Main technical features of Metrahit 27I

• Insulation resistance measurement 30.00 MOhm to 3.000 GOhm
• with adjustable test voltage of 50, 100, 250 or 500 V
• Milliohm meter
• 3000 mOhm to 300.00 mOhm with 1 A measuring current and
• 300 mOhm to 30.00 Ohm with 200 mA measuring current
• Kelvin connection (4-wire measurement)
• Resistance measurement from 300 Ohm to 30 MOhm
• Voltage measurement from 3 to 600 VDC and 3 to 600 VAC with ±30.000 digits
• Frequency measurement from 300 Hz to 3 kHz
• Temperature measurement with Pt 100, Pt 1000, Ni 100, Ni 1000
• DATA hold memory for up to 1200 measured values
• Continuity and diode testing
• Overload protection
• DAkkS calibration certificate as standard feature (saving for ISO9001)
• LCD including background illumination
• provided with 3 rechargeable NiMH batteries and a charger as standard equipment
• CAT II, IP54
• Optical interface
• Optional PC software METRAwin® 10/METRA HIT

Additional information: https://gossenmetrawatt.com/gmc/english/produkte/metrahit27i.htm

To buy in Estonia, please contact Energiatehnika Llt, info@energiatehnika.ee