Bus voltage may still be present12/04/2017During troubleshooting, it is often necessary to perform several checks to the Yaskawa G7 drive without power applied. If the drive has been in operation recently it is important to allow the DC bus voltage to dissipate before you make any checks to the drive. To begin this process always keep safety in mind. Before you make any checks without power, make sure that the three phase power is disconnected. Follow any lockout tag out procedures that are required at the source of power. The DC bus typically has 600 to 1400 volts on it during operation. Before touching any components inside the drive, look at the charge LED. If high voltage is present on the DC bus the charge LED will glow red. As the DC bus discharges the LED will fade out. If the drive has sustained any damage, particularly to the charging circuit, the charge LED may be off already. There is a possibility that high voltage will be present at the DC bus even when the charge LED is off. The photo to the right illustrates damage to the DS1 diode. With this component damaged, the charge LED will not operate at all to indicate that a voltage is present. To determine if the DC bus is completely discharged, measure between the positive and negative terminals of the drive with a DC voltmeter. Set the meter to its highest scale and place the positive lead onto the positive terminal and the negative lead on the negative terminal. If the measured voltage is below 10VDC it is safe to work inside the drive. The photo below illustrates the placement of meter leads on the DC bus terminals. The positive (red) meter lead is placed on the jumper between positive 1 and positive 2 DC bus terminals. The negative (black) meter lead is placed on the negative DC bus terminal. If you place the leads during the time the DC bus is dissipating, you will be able to observe the voltage level decreasing until it reaches a safe level. Ensuring the DC bus is discharged is mandatory before doing any work or troubleshooting in the drive. Failure to do these checks may result in serious injury or damage to the drive. If the charge LED is not lit, it may also be an indicator of further damage that may need to be repaired before power is reapplied to the drive. If you require assistance with these checks or are in need of repair, call on the experts at PES at 800-732-4695. Back To Blog
Bus voltage may still be present12/04/2017During troubleshooting, it is often necessary to perform several checks to the Yaskawa G7 drive without power applied. If the drive has been in operation recently it is important to allow the DC bus voltage to dissipate before you make any checks to the drive. To begin this process always keep safety in mind. Before you make any checks without power, make sure that the three phase power is disconnected. Follow any lockout tag out procedures that are required at the source of power. The DC bus typically has 600 to 1400 volts on it during operation. Before touching any components inside the drive, look at the charge LED. If high voltage is present on the DC bus the charge LED will glow red. As the DC bus discharges the LED will fade out. If the drive has sustained any damage, particularly to the charging circuit, the charge LED may be off already. There is a possibility that high voltage will be present at the DC bus even when the charge LED is off. The photo to the right illustrates damage to the DS1 diode. With this component damaged, the charge LED will not operate at all to indicate that a voltage is present. To determine if the DC bus is completely discharged, measure between the positive and negative terminals of the drive with a DC voltmeter. Set the meter to its highest scale and place the positive lead onto the positive terminal and the negative lead on the negative terminal. If the measured voltage is below 10VDC it is safe to work inside the drive. The photo below illustrates the placement of meter leads on the DC bus terminals. The positive (red) meter lead is placed on the jumper between positive 1 and positive 2 DC bus terminals. The negative (black) meter lead is placed on the negative DC bus terminal. If you place the leads during the time the DC bus is dissipating, you will be able to observe the voltage level decreasing until it reaches a safe level. Ensuring the DC bus is discharged is mandatory before doing any work or troubleshooting in the drive. Failure to do these checks may result in serious injury or damage to the drive. If the charge LED is not lit, it may also be an indicator of further damage that may need to be repaired before power is reapplied to the drive. If you require assistance with these checks or are in need of repair, call on the experts at PES at 800-732-4695.