WEG ECW500, User Manual

Page: 47 / 84

Functional Description .
ECW500 | 39
the decrement in the reference will occur continuously until the voltage applied to the digital input is removed or
until the minimum increment value is reached, which is equal to the rated value of the synchronous machine
configured on the ECW500.
NOTE!
This digital input has no complementary relationship with the INCREMENT digital input.
However, if the DECREMENT digital input is activated simultaneously with the INCREMENT, a fault
warning will be generated and the reference will not suffer modifications.
6.2.11 ALARM RESET Digital Input
This input resets the active alarms on the ECW500.
6.3 ANALOG INPUTS
The ECW500 has two isolated analog inputs which can be used to actuate in the reference of each mode of
operation or as a feedback signal for the MECC mode. For using the analog signal as reference, it is necessary
to adjust the parameter 31048 in option 1 (Analog Input) or in the option 2 (Par Analog Input).
These inputs accept signals in voltage (± 10 V) or current (4 mA to 20 mA), with specific terminals for each
signal type (V+/V- and I+/I-), but only one of the signals can be used to act in the reference. Signal type
selection to be used must be made via parameters 31054 and 31056, which define the function of each analog
input.
When the current input is selected, the ECW500 internally calculates a voltage equivalent in the scale from -10
to +10 V. The calculation is made based on the following equation
3
:
𝑉
𝑒𝑞
= 1.25 × (𝐼
4−20𝑚𝐴
𝑚𝑒𝑎𝑠𝑢𝑟𝑒𝑑
− 12)
In the MTVC or MTVC DROOP mode, the reference value that may be obtained through the analog input is
related to the rated voltage of the machine and is calculated by the relation below:
𝑉
𝑅𝑒𝑓_𝑀𝑇𝑉𝐶
= (𝐺𝑎𝑖𝑛
𝐴𝐼_𝑀𝑇𝑉𝐶
×
𝑉
𝐴𝐼_𝑚𝑒𝑎𝑠𝑢𝑟𝑒𝑑
10
× 𝑉
𝑟𝑎𝑡𝑒𝑑
) + 𝑂𝑓𝑓𝑠𝑒𝑡
𝐴𝐼_𝑀𝑇𝑉𝐶
In which:
MTVC AI
Gain
_
is the gain parameter for the analog input in the MTVC mode (parameter 30248);
measured AI
V
_
is the measured voltage at the analog input (parameter 40028);
rated
V
is the rated voltage of the synchronous machine set on the ECW500 (parameter 30058);
AI_MTVC
Offset
is the voltage
offset that can be added to the reference value (parameter 31068).
In the MECC mode, the reference value corresponding to the analog input can be between 0 and 100% of the
nominal excitation current, according to the equation:
𝐼
𝑅𝑒𝑓_𝑀𝐸𝐶𝐶
= 𝐺𝑎𝑖𝑛
𝐴𝐼_𝑀𝐸𝐶𝐶
×
𝑉
𝐴𝐼_𝑚𝑒𝑎𝑠𝑢𝑟𝑒𝑑
10
× 𝐼
𝐸𝑋𝐶_𝑟𝑎𝑡𝑒𝑑
In which:
MECC AI
Gain
_
is the gain parameter for the analog input in the MECC mode (parameter 30250);
3
On the MECC mode, the equivalent voltage calculation is done considering only the positive range (0 to + 10V). In that case the equation
for the conversion is as follows:
𝑉
𝑒𝑞
= 0.625 × (𝐼
4−20𝑚𝐴_𝑚𝑒𝑎𝑠𝑢𝑟𝑒𝑑
− 4)