• The RESET push-button must be a normally-open type with a
momentary contact when pushed.
• The electrical ratings must be at least 1 amp at 250 volts AC.
• Specific push-buttons may be sourced by manufacturers such
as Appleton Electric and Crouse Hindes, Inc.
Optional Push-button Calibration
The following procedure is used to enter the calibration by using
the push-button.
1. Press and hold the push-button until the ¶ heart is
displayed.
2. Release the push-button.
• At this time, any recoverable alarms will be
acknowledged.
3. Press and hold the push-button within three seconds of the
push-button release.
4. Release the push-button when the desired calibration is
displayed. See TABLE A-3.
Table A-3. Push-button Calibration
CALIBRATION TYPE DISPLAYED DATA
PUSH-BUTTON
HOLD TIME
Zero Calibration CAL ZERO 5 seconds
Span Calibration CAL SPAN 10 seconds
ICAL iCAL 20 seconds
• Refer to Chapter 2, "Startup and Calibration" for more
information on calibration.
5. The calibration can be aborted during the 30-second
countdown by pressing the push-button until the ¶! is
displayed.
• When the push-button is released, the calibration wil be
aborted.
Relay Connections
All electrical connections to internal relays can be made directly
on the pc board (see FIGURE A-5).
If you are connecting the relays to motors, fluorescent lighting or
other inductive loads, it is necessary to suppress any sparks or
inductive feedback that may occur at the relay contact. These
effects may render the unit inoperative. One way to reduce these
effects is to install a *Quencharc
®
across the load being switched.
This device is available from MSA as P/N 630413.
Appendix A, Internal Relay Option
A-10
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