Argon supply voltage troubleshooting

If there's problem getting rid of permanent under voltage fault in Argon, it may be caused by following reasons:

• STO1 input is not powered by 24 VDC
• Drive's internal fuse has blown. To check this safely discharge drive, remove cover, remove fuse and measure fuse resistance. If high current & power is demanded from the drive, then a higher amperage fuse may be installed in the place of original. Maximum fuse size is 16A slow blow and the factory default is between 6.3-8 A slow blow.
• Other failure in AC power path, see below for details.

Drive internal AC circuity

Inrush current limiter is based on a resistor which is bypassed by a GraniteCore controlled relay after HV DC supply has risen near nominal levels.

Verifying internal HV DC bus voltage can be done by reading the voltage value from Granity Testing tab or by measuring DC voltage between VP and VN terminals. The voltage between VP and VN is directly connected to the power stage, so if there is voltage between these terminals, then drive's HV supply is properly powered and it is possible to drive motor.

Checking for AC to HV DC signal path components

STO1

Applying 24V voltage to STO1 inputs causes the STO relay to emit a relay click sound. If there is no sound, then the reason is related to STO1 relay or it's control.

Fuse F1

Open drive case and check conductivity of fuse F1. See Replacing Argon fuse.

Inrush current limiter resistor R7

R7 is a 5W resistor from 33 to 100 ohm that conducts current to charge bulk capacitors. After capacitors are charged to full, relay RL2 is closed to allow high current flows.

Resistance of R7 can be measured with multimeter from test points marked in the image. The correct reading is the marked resistance +/- 2 ohm. It is possible to replace (desolder and solder) new resistor without removing heatsink from the PCB by approaching PCB from the side of the board.

It is recommended to replace R7 with similar size 5W 100 ohm resistor such as Farnell 987645

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Resistor R7 measurement points inside Argon

Reason for R7 burn

• R7 will burn (open circuit) if there is malfunction in relay RL2 (relay stuck in off-state).
• R7 will burn open if power is consumed from HV DC bus while relay RL2 is open (so drive tries to charge capacitor bank through this resistor without but voltage does not rise). This is possible if something is drawing power from VP and/or VN terminals. This could be another drive shared in the same bus, or for example a loose wire strand shorting wrong terminals in J4 connector.
• Another causes might be a damaged power stage or regenerative drive (some transistors short circuited) of drive, which also would load HV DC bus continuously. To identify if this has happened, see Determining Argon hardware failure.

Drive firmware disables power stage and regenerative resistor drive always when RL2 is open, but it can't prevent resistor burn in case of the conditions mentioned above.

AC/DC rectifier bridge B3

Measuring condition of B3 is possible with multimeter's diode check function. Check all four diodes from the test points marked in the image. Multimeter red lead goes to anode and black to cathode. All diodes should give reading of 0.4 to 0.5 Volts.

Diode bridge B3 measurement points circled

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