====== Electricity Meter ======

{{:cs:mervis-ide:35-help:t42_electricitymeter.png}}

==== 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 =====

<code>
program test
    var
        em: lib.hvac.v1_0.T42_ElectricityMeter;
    end_var

    em();
end_program
</code>

===== 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 <sup>1</sup>                                                       |      |
|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               |      |

<sup>1</sup> 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.