Calculating the Maximum Wire Length - PENN Controls - VFD68Bxx - VFD68Cxx - VFD68Dxx - Three‐Phase Motor Speed Controller - VFD68 Three‐Phase Variable Frequency Drive

About this task

Use the recommended wire size in accordance with local, national, and regional regulations to determine the electrical resistance of the wire (R) according to Table 1.

Table 1. Electrical Resistance by Wire Size

Recommended Wire Size1	Electrical Resistance of Wire (milliohms/meter)
25 mm2	0.727
21.2 mm2 (4 AWG)	0.815
16 mm	1.15
13.3 mm2 (6 AWG)	1.30
10 mm2	1.83
8.3 mm2 (8 AWG)	2.06
6 mm2	3.08
5.3 mm2 (10 AWG)	3.28
4 mm2	4.61
3.3 mm2 (12 AWG)	5.21
2.5 mm2	7.41
2 mm2 (14 AWG)	8.28
1.5 mm2	12.1

Find the rated voltage (V) and maximum output current (I) from the rating plate on the selected VFD68 drive. Use Figure 1 to determine the maximum recommended wiring length for the VFD68 drive.

Figure 1. Maximum Wire Length Calculation

Note: If the maximum wire length needs to be extended, select a larger wire size and recalculate the maximum wire length. Do not exceed 100 m.

Note: Maximum wiring length is also affected by the setting of P. 72. See PWM Frequency, Audible Motor Noise, and EMI.

The following example looks for the maximum wiring length for a VFD66BGG-2C model.

1. Table 1 indicates that a VFD66BGG-2C model is a 230 VAC drive, rated for 1.49 kW (2 HP).
2. The rating information plate (Figure 1) for that model indicates that the VFD66BGG drive has a voltage rating of 230 VAC and a maximum output rating of 7 amperes.
3. Table 1 gives the recommended wire size as 14 AWG.
4. Table 1 shows 14 AWG size wire as having an electrical resistance of 8.28 milliohms/meter.
5. Using the equation in Figure 1 and using the values we found in the preceding steps:

   (11.5 * 230) / (7 * 8.28) = 2656.6 / 57.96 = 45.8

   The maximum wire length is 45.8 meters.