Utility-To-Utility Application; Generator-To-Generator Application; Ejp Function; Control Of Changeover Devices - LOVATO ELECTRIC ATL20 Manual Operativo

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UTILITY-TO-UTILITY APPLICATION

– In the utility-to-utility (U-U) application, the load is usually connected to the main utility and the transfer to the secondary utility occurs at main line anomaly
or when a transfer signal is given externally.

GENERATOR-TO-GENERATOR APPLICATION

– In this case, two generators are controlled, each with a start-stop relay and feedback signals, if any.
– In this application, a rotation between generators can be programmed, i.e. the load can be shifted from one to the other at regular intervals, with the purpose
of sharing out the generator operation equally.
– It is also possible to set the time of day when rotation shall occur, so that load supply cut-off occurs at a specified time.
– In case of a problem to either generator, the load is shifted to the one in stand-by in all cases.

EJP FUNCTION

– For applications requiring the EJP (special electricity tariff) function, it is possible to use two programmable inputs set to functions S.GE (start generator) and
E.tr (External transfer).
– Parameter P2.26 can also be used to define a generator start delay.

CONTROL OF CHANGEOVER DEVICES

– For the line changeover, ATL can control different types of devices such as motorised circuit breakers, motorised changeover switches or contactors.
– Depending on the type of changeover devices used with the ATL, appropriate wiring diagrams must be used with related programming of programmable
inputs / outputs.
– Programmable outputs are set as default for the application with motorised circuit breakers.
See the attached wiring diagrams at the end of this manual.
– The device status feedback inputs shall be normally wired, so as to ensure reliable system operation.
– Nonetheless, it is possible to avoid their wiring and set programmable inputs for other functions. In this case, the unit operates as if the device carried out
the command sent at once.
– If the device status feedback inputs are not used, then ATL, after power-on, sends an open command to bring the switching devices in a determinate position.
– If instead the device status feedback inputs are used, then ATL, after power on, does not send commands to the switching device until the relative line status
is stable, that is when the
presence / absence delay have elapsed.
– Internal control relays are neither electrically nor mechanically interlocked.

CONTROL OF MOTORISED CIRCUIT BREAKERS

– For the control of motorised circuit breakers, 4 outputs are needed (open and close commands for line 1 and line 2) and two inputs for circuit breaker status
feedback, plus any additional optional inputs for alarm signalling (WITHDRAWN and TRIP).
– Open and close commands can be maintained in continuous or pulse mode, i.e. maintained until the circuit breaker has reached the required position + safety
time.
– The two command modes can be selected through the appropriate parameter P2.07, set on "COn" or "PUL" in the general data menu.
– TRIP inputs are ignored for a 15-second window every time an open command is sent to circuit breakers. This prevents a false alarm from being activated if
the circuit breakers temporarily send a TRIP signal while breaking through their release coil.
– A 0.5-second interval is interposed between the opening and closing commands of the same circuit breaker.
– If feedback inputs are used, should the circuit breaker not close, a second attempt is conducted before generating the alarm.

CONTROL OF MOTORISED CHANGEOVER SWITCHES

– The application with motorised switches is very similar to the previous one, but provides for the use of three outputs only (line 1, line 2 and all open
positions) and two inputs for switch status.
– CL.1, CL.2 and OP.A output functions and Fb.1 and Fb.2 input functions are required.
– Pulse or continuous command mode can also be selected.

CONTROL OF CONTACTORS

– If a pair of contactors is used, two outputs (CL.1 and CL.2) and two status inputs are required.
– In this case, the command must be programmed in control mode for contactors (P2.07 = Cnt).

VOLTAGE CONTROLS

– All the conditions which can help establish whether a power source is or is not suitable are defined by the user through menu P1 (ratings) and menus P3 and
P4 (line 1 and line 2 voltage limits, respectively).
– The system ratings can be set through menu P1, including rated voltage and frequency, which will be used as reference to set percentage thresholds.
– A transformation ratio (VT) can be set whenever a voltage lower than the actual system voltage is applied to the unit voltage inputs. Also in this case, both
the viewing and the setting of thresholds will be implemented in actual magnitudes referred to the system.
– The controller can be programmed to perform voltage controls on three-phase with or without neutral, two-phase or single-phase systems (P1.03).
– In the case of three-phase or two-phase systems, L-L or L-N voltage, or both controls can be chosen (P1.04). In every case, the rated voltage set with P1.01
has to be equal to the phase-to-phase voltage.
– The following table lists the controls made on each line. The ones marked with OFF are excluded.
Control Description
Minimum voltage One or more phases too low
Maximum voltage One or more phases too high
Phase loss Threshold below which the unit trips quicker than with a normal decrease
Asymmetry (unbalance) Phases within the maximum-minimum range but too different from each other
Minimum frequency Too low frequency
Maximum frequency Too high frequency
Phase sequence Reverse rotation of phases
G
B
OFF
G
G
G
G
G
G