Total wiring length (example of 400 V class inverter of the FR-CS84-120 or higher) 1 100 m 2 100 m or less 50 m When driving a 400 V class motor by the inverter, surge voltages attributable to the wiring constants may occur at the motor 100 m + 50 m = 150 m 3 terminals, deteriorating the insulation of the motor. In this case, take one of the following measure. • Use a "400 V class inverter-driven insulation-enhanced motor" and set Pr.72 PWM frequency selection according to the wiring length.
5 5 6 • Especially for long-distance wiring, the inverter may be affected by a charging current caused by stray capacitances of the wiring, leading to an activation of the overcurrent protection, malfunction of the fast-response current limit operation, or even fast-response current limit function malfunctions, disable this function. (Refer to Pr.156 Stall prevention operation selection on to an inverter failure. It may also cause a malfunction or fault of the equipment connected ON the inverter output side. If the page 119 .) 7 • Refer to page 59 to drive a 400 V class motor by the inverter. • For the details of PWM frequency selection , refer to page 92 .
8 2.5.4 Earthing (grounding) precautions Always earth (ground) the motor and inverter. 9 Purpose of earthing (grounding) Generally, an electrical apparatus has an earth (ground) terminal, which must be connected to the ground before use. An electrical circuit is usually insulated by an insulating material and encased. However, it is impossible to manufacture an 10 insulating material that can shut off a leakage current completely, and actually, a slight current flows into the case. The purpose of earthing (grounding) the case of an electrical apparatus is to prevent operators from getting an electric shock from this leakage current when touching it.
To avoid the influence of external noises, this earthing (grounding) is important to audio equipment, sensors, computers and other apparatuses that handle low-level signals or operate very fast. Earthing (grounding) methods and earthing (grounding) work As described previously, earthing (grounding) is roughly classified into an electrical shock prevention type and a noise- be done to prevent the leakage current having the inverter's high frequency components from entering the malfunction influenced malfunction prevention type. Therefore, these two types should be clearly distinguished, and the following work must prevention type earthing (grounding): 33 2.
INSTALLATION AND WIRING 2.5 Main circuit terminals Wiring length 50 m or shorter Wiring length 50 to 10 m Any setting 8 (8 kHz) or lower NOTE