Powering WMT700 - WMT700

WMT700 Series User Guide

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User guide
WMT700 has separate power supply inputs for:
  • Operating power
  • Heating power
The inputs are usually connected to the same 24 V DC power supply unit. Special applications, such as battery operation or battery backup, may require separate supplies.

The operating power has 1 supply terminal and 1 ground terminal, while the heating power has 2 supply terminals and 2 ground terminals allowing a higher supply current. All supply ground terminals are internally connected to each other inside WMT700.

Make sure that the power supply output voltage, current, and power specifications including the tolerance match the WMT700 specifications.
In a system setup with 2 separate power supplies, avoid ground potential differences between the supplies. Connect the negative terminals together if necessary.
Do not use a DC power supply based on a chopper circuit that operates at 100 kHz. The ripple in the DC output can distort the measurement.

The sensor and the cabling must be protected with a fuse or a circuit breaker. The maximum sizes of the fuses or circuit breakers protecting the power lines:

  • 13 A with type B, C, or D (IEC/EN 60898-1 or UL 1077) tripping characteristics and specified for at least 40 V DC voltage operation for heating power supply.
  • 1 A with type B (IEC/EN 60898-1) tripping characteristics and specified for at least 40 V DC voltage operation for operating power supply.

The circuit breaker can be either 2-pole (on both positive and negative/ground) or 1-pole (positive wires). You can also replace the circuit breaker with a cartridge fuse with T (slow acting) tripping characteristics.