IMPULSE
®
•G+ & VG+ Series 4 Technical Manual
November 2020
Page 30
3 Wiring
3.1 Wiring Practices
• Recommended wire is to be rated for minimum 75°C, 600 VAC, vinyl sheathed.
• Ensure that the encoder wiring is less than 300 feet unless fiber optic cables are used.
• Ensure that the encoder wiring is isolated from the power wiring.
• Ensure that the encoder wiring shield is grounded only at the VFD end.
• Connect the incoming three-phase AC source to terminals R/L1, S/L2, T/L3.
• Connect the Motor leads to terminals U/T1, V/T2, W/T3.
• Install a line reactor between the output of the VFD in applications that require a disconnecting means between
the VFD’s output and motor. Use a “make before break” auxiliary contact with the disconnect means and the
hardware base block of the VFD.
• Use hard contacts between the PLC output and the VFD 120/24/48 VAC interface board. If using a solid state
output from a PLC (TRIAC) to a 120/24/48 VAC input card, use a 5KΩ, 5W resistor between the signal and X2.
• If the power source is 500 kVA or greater, or more than 10 times the VFD kVA rating, ensure that there is at
least 3% impedance between the power source and the VFD input. To accomplish this, a DC reactor can be
installed between VFD terminals +1 and +2, or an AC line reactor can be used on the input of the VFD.
Excessive peak currents could damage the input power supply circuit if there is not enough impedance
provided.
• Comply with Section 3.2 on page 33.
• Use time delay fuses, which are sized at 150% of VFD’s continuous rated input current, for wiring protection.
• Use appropriate R-C or MOV type surge absorbers across the coil of all contactors and relays in the system.
Failure to do so could result in noise-related, nuisance fault incidents.
• Use external dynamic braking resistors for all applications.
• Do not ground the VFD with any large-current machines.
• Before using any welding or high-current machines near the crane, disconnect all line and ground wiring.
• Do not let the wiring leads come in contact with the VFD enclosure.
• Do not connect power factor correction capacitors to the VFD input or output; use a sine wave filter.
• When possible, hard-wire the VFD and motor. Do not use sliding collector bars (e.g., festoon cable).
• If there is a user input device or interface board that is remote, use shielded cable between the VFD input
terminals and the interface output terminals or user input device(s).
• Before turning on the VFD, check the output circuit (U/T1, V/T2 and W/T3) for possible short circuits and
ground faults.
• Increase the wire size by one gauge for every 250 feet (76.2 meters) between the VFD and motor; suggested
for center driven cranes, trolleys, and bridges (voltage drop is significant at low frequencies).
WARNING
Before you wire the VFD, review the following practices to help ensure that your system is wired properly.
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