Precision Digital PD6400 - Manual (Page 56)

Model PD6400 High Voltage & Current Meter Instruction Manual
56
Relay Operation Details
Overview
The relay capabilities of the meter expand its usefulness beyond simple
indication to provide users with alarm and control functions. These
capabilities include front panel alarm status LEDs as well as either 2 or
4 optional internal relays and/or 4 external relays expansion module.
Typical applications include monitoring of high voltages and currents
having to do with applications related to generators, voltage monitoring,
current monitoring, or detecting locked rotor conditions. There are three
basic ways the relays may typically be used:
1. High or Low Alarms with Latching or Non-Latching Relays
2. Simple On/Off Control with 100% Adjustable Deadband
3. Sampling (Based on Time)
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. The following table
indicates how the alarm LEDs and relays will react on power-up based
on the set and reset points:
Alarm
#
HI or LO
Alarm
Set
Point
Reset
Point
Power-Up
Reading
Relay &
LED
1 HI 250 200 199 Off
2 LO 200 250 199 On
3 LO 100 150 199 Off
4 HI 150 100 199 On
Fail-Safe Operation
The following table indicates how the relays behave based on the fail-
safe selection for each relay:
Fail-Safe
Selection Non-Alarm State Alarm State Power Failure
NO NC NO NC
Off Open Closed Closed Open Relays go to
non-alarm state
On Closed Open Open Closed Relays go to
alarm state
Note: NO = Normally Open, NC = Normally Closed. This refers to the
condition of the relay contacts when the power to the meter is off.