BESTlogic Programmable Logic
BE1-951
7-6
Comments: x = virtual output designator A or 1 - 15
equation = Boolean logic expression using variables: virtual inputs (Ix), logic module outputs,
virtual outputs (VOx) and operators AND (
W
), OR (+), and NOT (/). Area G or S password
access is required to change settings.
Entering SL-VO by itself will normally read the output logic equation of the active logic. If entered while
programming a custom logic, it will read the output logic of the custom logic.
SL-VO Command Examples
1.
Turn on output 5 when the breaker failure logic trips.
>SL-VO5=BFT
2.
Turn on output 1 when any instantaneous or timed overcurrent element trips.
>SL-VO1=50TPT+50TN+150TP+150TN+51P+51N+50TQ+51Q
3.
Turn on output 2 when the low-set instantaneous overcurrent element (50) trips but the corresponding
high-set instantaneous overcurrent element (150) does not.
>SL-VO2=50TP
W
/150TP+50TN
W
/150TN
Virtual and Hardware Outputs
A virtual output exists only as a logical state inside the relay. A hardware output is a physical relay contact
that can be used for protection or control. Each BE1-951 relay has five isolated, normally open (NO) output
contacts (OUT1 – OUT5) and one isolated, normally closed (NC) alarm output (OUTA). Output contacts
OUT1 through OUT5 are controlled by the status of the internal virtual logic signals VO1 through VO5. If
VO[n] becomes TRUE, then the corresponding output relay OUT[n] energizes and closes the NO contacts.
For the alarm output, if VOA becomes TRUE, the ALM output de-energizes and opens. More information
about input and output functions is provided in Section 3
Input and Output Functions.
Hardware outputs can also be controlled by the CO-OUT (control operate, output) command. The CO-OUT
command overrides control of logic outputs. Outputs may be pulsed or latched in a 0 or 1 state
independently from the state of the virtual output logic. More information about overriding control of logic
outputs is available in Section 3,
Input and Output Functions.
LOGIC SCHEMES
A logic scheme is a group of logic variables written in equation form that defines the operation of a multi-
function relay. Each logic scheme is given a unique name of one to eight alphanumeric characters. This
gives you the ability to select a specific scheme and be confident that the selected scheme is in operation.
Six logic schemes, configured for typical protection applications, are stored in nonvolatile memory. Only one
of these logic schemes can be active at a given time. In most applications, preprogrammed logic schemes
eliminate the need for custom programming. Preprogrammed logic schemes may provide more inputs,
outputs, or features than are needed for a particular application. This is because the preprogramed schemes
are designed for a large number of applications with no special programming required. Unneeded inputs or
outputs may be left open to disable a function, or a function block can be disabled through operating
settings. Unused current sensing inputs should be shorted to minimize noise pickup.
When a custom logic scheme is required, programming time can be reduced by copying a preprogrammed
scheme into the active logic. The logic scheme can then be modified to meet the specific application.
The Active Logic Scheme
Digital, multifunction relays must have an active logic scheme in order to function. All Basler Electric
multifunction relays are delivered with a default, active logic loaded into memory. The default, active logic
scheme for the BE1-951 is named BASIC-OC. If the function block configuration and output logic of
BASIC-OC meets the requirements of your application, then only the operating settings (power system
parameters and threshold settings) need to be adjusted before placing the relay in service.
