Yaskawa P-7 Variable Frequency Drive (VFD) FAQ

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Click on a question below to show the solution:

With power supplied to the drive, three values appear on the display. What exactly do these numbers mean?

Example Display:

The upper value should read parameter U1-02, this is the real-time output frequency of the inverter measured 0-60 in Hertz. This should, with multiple dryers running, be fluctuating constantly.

The middle value should read U1-38, this is the set-point in inches water column at which the drive will initialize. Under normal conditions it should ALWAYS be .12”w.c.

The bottom value should read U1-24, this is the real-time backpressure in inches water column the dryers are experiencing. Once the value exceeds .12” w.c., the drive will initialize automatically and fluctuate the output in hertz (speeding and slowing the fan) in an effort to maintain a desired backpressure of .12”w.c. If this value is higher than the value shown in U1-38, and the fan is not running, call Energenics for support at 800-944-1711.

How should the pressure tubing be plumbed into the pressure transducer?

The pressure transducer is the small box connected by 3 wires to the drive. The tubing should be run from the intake of the lint collector (high pressure side pre-screen on the filter) into the high port on the transducer without kinks or restrictions. Plumbing it to the low port will produce an inactive drive.

After reviewing the first two FAQ answers I still cannot identify the problem, what do I check next?

Make sure the pressure tubing has no kinks, cracks, or lint built up inside it, disconnect both ends of the hose and use compressed air to clean the tubing out. Verify the wiring from the transducer matches the drawing shown on the inside of the panel. Also verify there is a jumper wire installed between terminals S1 and SN on model P-7. For model V-1000 the jumper should be between SC and S1. Using a multi-meter, ensure the proper voltage is supplied to the inverter.