Functions, monitoring, and protective functions
9.4 Monitoring and protective functions
Inverter chassis units
Operating Instructions, 07/2016, A5E00331449A
491
Measuring the cable resistances
When using 2-wire sensors (1x2, 2x2 wire systems), to increase the measuring accuracy,
the cable resistance can be measured and saved.
Procedure for determining the cable resistance:
1. Select the measuring method (1x2/2x2) for the corresponding terminal block (p4108[0...5]
= 0, 1).
2. Set the required sensor type for the relevant channel (p4100[x] = 1 ... 6, x = 0...5 or
0...11).
3. Bypass/jumper the sensor to be connected (short-circuit the sensor cable close to the
sensor).
4. Connect the sensor cables to the relevant terminals 1(+), 2(-) or 3(+), 4(-).
5. For the corresponding channel, start measurement of the cable resistance (p4109[x] = 1).
6. After p4109[x] = 0, check the measured resistance value in p4110[x].
7. Remove the jumper across the temperature sensor.
The measured cable resistance is then taken into account when evaluating the temperature.
The cable resistance value is saved in p4110[0...11].
Note
Cable resistance
The value for the cable resist
ance can also be directly entered into p4110[0...11].
A line filter is available to suppress radiated noise. Using p4121, the filter can be set to a 50
Hz or 60 Hz rated line frequency.
Measurement with up to 6 channels
Temperature measurement with a sensor in 2-wire technology
With p4108[0...5] = 0, you sense the signals from a sensor in 2-wire technology at a 4-wire
connection at terminals 1(+) and 2(-).
Terminals 3 and 4 remain open.
Temperature measurement with a sensor in 3-wire technology
With p4108[0...5] = 2, you sense the signals from a sensor in 3-wire technology at a 4-wire
connection at terminals 3(+) and 4(-).
The measuring cable is connected at terminal 1 (+).
You must short-circuit terminals 2 (-) and 4 (-).
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