Table of Contents
Electricity Meter
Full Name
Lib.Hvac.v1_0.T42_ElectricityMeter
Description
Counters for active, inductive, and capacitive components of energy. Processing of quarter-hours and energy time derived from the quarter-hour signal.
Required Project References
- Lib.Hvac
Usage in ST
program test
var
em: lib.hvac.v1_0.T42_ElectricityMeter;
end_var
em();
end_program
Description of Inputs and Outputs
| Inputs | Name | Data Type | Retain | Required Connection | Meaning |
| q | udint | No | No | Synchronization input for the quarter-hour signal (quarter-hour counter) | |
| x_act | real | No | No | Counter input for the active component of energy | |
| x_ind | real | No | No | Counter input for the inductive component of energy | |
| x_cap | real | No | No | Counter input for the capacitive component of energy | |
| bx_act_rst | bool | No | No | Reset counter for the active component of energy | |
| bx_cap_rst | bool | No | No | Reset counter for the capacitive component of energy | |
| bx_ind_rst | bool | No | No | Reset counter for the inductive component of energy | |
| Ky0_act | real | Yes | No | Q constant linear transformation for the active component of energy | |
| Ky0_ind | real | Yes | No | Q constant linear transformation for the inductive component of energy | |
| Ky0_cap | real | Yes | No | Q constant linear transformation for the capacitive component of energy | |
| K_act | real | Yes | No | K constant linear transformation for the active component of energy | |
| K_ind | real | Yes | No | K constant linear transformation for the inductive component of energy | |
| K_cap | real | Yes | No | K constant linear transformation for the capacitive component of energy | |
| q_offset | int | Yes | No | Maximum time difference from exact quarter-hour relative to the last quarter-hour signal in [s], mechanism see description |
| Outputs | Name | Data Type | Meaning |
| e_time | dt | Energy time according to the quarter-hour signal (max. 15min difference against PLC time) | |
| q_time | real | Time in the current quarter-hour | |
| q_order | real | Order of the quarter-hour in the day | |
| q_signal | real | Quarter-hour signal 1 | |
| y_act | real | Value of the active counter without transformation | |
| y_ind | real | Value of the inductive counter without transformation | |
| y_cap | real | Value of the capacitive counter without transformation | |
| Ky_act | real | Value of the active counter after transformation | |
| Ky_ind | real | Value of the inductive counter after transformation | |
| Ky_cap | real | Value of the capacitive counter after transformation | |
| cos_fi | real | Power factor | |
| sync_err | bool | Quarter-hour signal failure indication | |
| q_start | dt | Timestamp of the start of the current quarter-hour | |
| time_diff | int | Time difference - energy time obtained from the quarter-hour vs. PLC time |
1 Signaling is performed by a transition from false to true, lasting for 5 seconds, and then returning to false
Detailed Function Description
Counters are protected against overflow, and linear transformations Ky_X = K_X*y_X + Ky0_X can be set for each component. It works with energy; if power processing is required, an integrator functional block must be added in advance. Mechanism for handling quarter-hour signal failure. If two consecutive quarter-hour signals differ by more than the q_offset input defines in seconds, the quarter-hours will be controlled by RTC and the sync_err signal will be set.