Danaher Motion 601...620 Product Manual
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Contents
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6.9 Shock-hazard protection6.9.1 Leakage currentLeakage current via the PE conductor results from the combination of equipment and cable leakagecurrents. The leakage current frequency pattern comprises a number of frequencies, whereby theresidual-current circuit breakers definitively evaluate the 50Hz current. For this reason, the leakagecurrent cannot be measured using a conventional multimeter.As a rule of thumb, the following assumption can be made for leakage current on our low-capacitycables at a mains voltage of 400 V, depending on the clock frequency of the output stage:I leak = n x 20mA + L x 1mA/m at 8kHz clock frequency at the output stageI leak = n x 20mA + L x 2mA/m at a 16kHz clock frequency at the output stage(where Ileak =leakage current, n=number of amplifiers, L=length of motor cable)At other mains voltage ratings, the leakage current varies in proportion to the voltage.Example: 2 x servo amplifiers + a 25m motor cable at a clock frequency of 8kHz:2 x 20mA + 25m x 1mA/m = 65mA leakage current.Since the leakage current to PE is more than 3.5 mA, in compliance with EN50178the PE connection must either be doubled or a connecting cable with across-section >10mm² must be used. Use the PE terminals (X0A and X0B) or the PEbolt in order to fulfil this requirement.The following measures can be used to minimise leakage currents.— Reduce the length of the engine cable— Use low-capacity cables (see p.42)— Avoid mains asymmetries (with an isolating transformer)6.9.2 Residual-current circuit breakers (FI)In conformity with DIN IEC 60364-4-41 – Regulations for installation and EN 60204 – Electricalequipment of machinery, residual-current circuit-breakers (called FI below) can be used providedthe requisite regulations are complied with.The SERVOSTAR 600 is a 3-phase system with a B6 bridge. Therefore, FIs which are sensitiveto all currents must be used in order to detect any d.c. fault current. Refer to chapter 6.9.1 for therule of thumb for determining the leakage current.Rated residual currents in the FI10 -30 mA Protection against "indirect contact" (personal fire protection) for stationary and mo-bile equipment, as well as for "direct contact".50 -300 mA Protection against "indirect contact" (personal fire protection) for stationary equip-mentRecommendation: In order to protect against direct contact (with motor cablesshorter than 5 m) we recommend that each servo amplifier be protectedindividually using a 30mA residual-current circuit-breaker which is sensitive to allcurrents.If you use a selective FI circuit-breaker, the more intelligent evaluation process will prevent spurioustripping of the circuit-breakers.32 SERVOSTAR ® 601...620 Product ManualTechnical description 07/2007 Danaher Motion |
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