ME440 & ME435 main difference is that ME435 does not measure the neutral

While to ME435 power meter remains in use, the main difference between the ME435 power meter and the ME440 power meter is that the ME435 does not measure neutral. Hence, the ME435 power meter is designed for measuring power in a three-phase electrical system where the neutral conductor is not required for power measurement. This is often referred to as a "three-wire" or "delta" configuration. In such systems, the neutral conductor carries little to no current because the load is balanced across the three phases.