Toshiba H9 operation manual System Grounding, Grounding Capacitor

System Grounding

Proper grounding helps to prevent electrical shock and to reduce electrical noise. The H9 ASD is designed to be grounded in accordance with Article 250 of the 2005 NEC or Section 10/Part One of the Canadian Electrical Code (CEC).

The grounding conductor shall be sized in accordance with Article 250-122of the NEC or Part One-

Table 6 of the CEC.

T h e M e t a l O f C o n d u i t I s N o t A n A c c e p t a b l e G r o u n d .

The input, output, and control lines of the system shall be run in separate metal conduits and each shall have its own ground conductor.

ASDs produce high-frequency noise — take steps to avoid the negative effects of noise. Listed below are some examples of measures that will help to combat noise problems.

•DO NOT install the input power and output power wires in the same duct or in parallel with each other, and do not bind them together.

•DO NOT install the input/output power wires and the wires of the control circuit in the same duct or in parallel with each other, and do not bind them together.

•Use shielded wires or twisted wires for the control circuits.

•Ensure that the grounding terminals (G/E) of the H9 ASD are securely connected to ground.

•Connect a surge suppressor to every electromagnetic contactor and every relay installed near the ASD.

•Install noise filters as required.

The Grounding Capacitor Switch and the 3-phase input and output terminals are shown on pg. 16 (see pg. 5 for more information on the Grounding Capacitor Switch).

Grounding Capacitor

The Grounding Capacitor plays a role in minimizing the effects of leakage current through the ASD system and through ground paths to other systems. Leakage current may cause the improper operation of earth-leakage current breakers, leakage-current relays, ground relays, fire alarms, and other sensors

— and it may cause superimposed noise on CRT screens.

The Grounding Capacitor Switch allows the user to quickly change the value of the leakage-reduction capacitance of the 3-phase input circuit. See figures 4, 5, 6, and 7 on pg. 19 for an electrical depiction of the leakage-reduction functionality and the methods used to change the capacitance value. The method used is typeform-specific.

If using a 460-volt 5 HP ASD or a 460-volt ASD that is in the range of 7.5 HP to 25 HP, and the U/T1, V/T2, and W/T3 connections to the motor are 100 meters or more in length, the ASD Carrier Frequency must be set to 4 kHz or less when activating or deactivating the Grounding Capacitor Switch. ASD overheating may occur if the Carrier Frequency is set above 4 kHz when activating or deactivating the Grounding Capacitor Switch.

See pg. 5 for more information on the Grounding Capacitor Switch and pg. 16 for the location.

18 H9 ASD Installation and Operation Manual