YASKAWA V7 Technical Manual

Also see for SI-T/ V7: Instructions

Contents

- xiii -DefinitionsSequence – refers to how the drive is started, stopped, and told which direction to run.When the sequence comes from the digital operator (local), the drive is started and stoppedusing the “RUN” and “STOP” keys on the digital operator, and direction is given via the“FWD/REV” key. Sequence can also come from the drive’s control terminals (remote)using either two-wire or three-wire control. The sequence inputs to the drive do NOT requireany outside voltages to activate them. Instead, contact closures (either from switches, relaycontacts or open collector circuits) activate the sequence inputs. Other sequence sources areavailable; consult Paragraph 5.13, Local/Remote Reference and Sequence Selection for details.Two-wire sequence – utilizes a “maintained” switch or relay contact. It is used on appli-cations where it is desirable to have the drive restart on restoration of power. Itshould not be used where safety of attending personnel might be threatened by arestart. This method is generally restricted to unattended fans & pumps, or whereanother controller is entrusted with the decision to restart. Direction is controlled by main-taining either a forward run or a reverse run command.Three-wire sequence – utilizes “momentary” buttons or switches. This controlscheme emulates the traditional 3-wire motor starter control. A momentary closure ofa normally open run switch latches the drive in the RUNmode (STOP switch must be closed or the drive will notaccept the momentary RUN command). A momentaryopening of the normally closed STOP switch unlatchesRUN mode bringing the drive to a stop. The three-wiresequence is used where it would be dangerous for thedrive to restart after a power outage. This methodrequires an intentional restart, as the RUN command isunlatched immediately on loss of power. Direction isdetermined by another maintained contact closure (closed = reverse).Reference – The frequency reference tells the drive how fast to run the motor. There are severalsource options for the frequency reference. First, the frequency reference can come from thedigital operator (local). Simply put, the motor speed can be entered into the keypad. Second, thefrequency reference can come from an analog signal (remote), such as 0 to 10 Volts DC. When0 Volts is applied to the drive, the drive will run at zero speed. When 10V is applied to the drive,it will run at full speed. Apply anything in between and the drive will run at that correspondingfrequency (2.5VDC = 25% speed = 15 Hz). Other reference sources are available; consultParagraph 5.11, Frequency Reference Selection for details.Local Control – when the sequence and/or reference comes from the digital operator.Remote Control – when the sequence and/or reference comes from the control terminals.STOPSTARTS1S2SCStartStop3-Wire Sequence