PD2-6400
Helios High Voltage & Current Meter
www.predig.com
9
Relays for Alarm & Control Applications
Adding relays to the Helios meter turns it into a sophisticated alarm device as well as a powerful, yet simple, alternative to a
more complicated PLC system for control applications. The Helios can be equipped with four 3 A Form C (SPDT) internal relays.
Relays are highly user-configurable as the following screen shot from MeterView Pro indicates:
Setting Set and Reset Points (HI / LO Alarms)
All relays are independent of each other and may be
programmed as high or low alarms with user desired set and
reset points. Setting a set point above a reset point results in
a high alarm and setting a set point below a reset point results
in a low alarm. Alarms have 0 – 100% deadband and set and
reset points may be set anywhere in the range of the meter.
Resetting the Relays (Action in MV Pro)
All relays are independent of each other and may be
programmed to reset (
Action
in MV Pro) in the following ways:
•
Automatic:
Alarm will reset automatically once the alarm
condition has cleared.
•
Automatic/Manual:
Alarm will reset automatically once the
alarm condition has cleared but can also be reset at any
time with a switch wired across terminals F4 and Common*.
•
Latching:
Alarm must be reset manually and can be done
so at any time with a switch wired across terminals F4 and
Common*.
•
Latching with Reset after Cleared:
Alarm must be
reset manually and can only be done so after the alarm
condition has cleared with a switch wired across terminals
F4 and Common*.
* Or via one of the four digital inputs
*Values are intended to show programming choices. They are not intended to represent an actual application.
Time Delay (On and Off)
In many applications it is desirable to wait before turning off
or on a relay – such as waiting for a process to settle before
taking action. Each relay on the Helios can be programmed
with independent on and off time delays of 0 to 999.9 seconds
to achieve this.
Relays Auto Initialization
When power is applied to the meter, the front panel LEDs and
alarm relays will reflect the state of the input to the meter.
Signal Loss or Current Input Break Relay Operation
When the meter detects a break in the current input, the relay
will go to one of the following selected actions:
1
Turn On (Go to alarm condition)
2
Turn Off (Go to non-alarm condition)
3
Ignore (Processed as a low signal condition)
User Selectable Fail-Safe Operation
All relays are independent of each other and may be
programmed for user selectable fail-safe operation. With the
fail-safe feature activated, the relays will transfer to the alarm
state on power loss to the meter.
