Alarm 1 and Alarm 2 output through the 654019 Alarm Relay Assembly is provided by two identical single-pole, double -throw relays. These relay contacts are rated at the following values:
5 amperes | 240 | VAC resistive |
1 ampere | 240 | VAC inductive |
5 amperes | 120 | VAC resistive |
3 amperes | 120 | VAC inductive |
5 amperes | 30 | VDC resistive |
3 amperes | 30 | VDC inductive |
Removal of AC power from the analyzer (such as power failure) de-energizes both relays, placing them in alarm condition. Switching characteristics of the Alarm 1 and Alarm 2 relays are as follows:
The Alarm 1 relay coil is de-energized when the display moves downscale through the value that corresponds to setpoint minus deadband. This relay coil is energized when the display moves up- scale through the value that corresponds to setpoint plus deadband.
The Alarm 2 relay coil is de-energized when the display moves upscale through the value that corresponds to the setpoint plus deadband. This relay coil is energized when the display moves downscale through the value that corresponds to setpoint minus deadband.
Both the ALARM 1 and ALARM 2 functions generally incorporate automatic rest. When the display goes beyond the preselected limits, the corresponding relay is de-energized. When the display returns within the acceptable range, the relay is turned on.
The ALARM 1 and/or ALARM 2 alarm functions may be converted to manual re- set. The conversion requires the substitution of an external pushbutton or other momentary contact switch for the jumper that connects the RESET terminals on the Alarm Relay Assembly. If the corresponding relay is now de-energized (i.e., in alarm condition), the relay remains
de-energized until the operator momentarily closes the switch.
By appropriate connection to the double -throw relay contacts, it is possible to obtain either a contact closure or a contact opening for an energized relay. Also, either a contact closure or a contact opening may be obtained for a de-energized relay. It is important, for fail-safe applications, that the user understands what circuit conditions are desired in event of power failure and the resultant relay de-energization. Relay contacts should then be connected accordingly (See Figure 2-5, page 2-8).
The ALARM 1 and ALARM 2 circuits have independent setpoint and deadband adjustments (See Figure 3-1, page 3-3). Ini- tially, the ALARM 1 and ALARM 2 Setpoint Adjustments must be calibrated by means of the ALARM 1 and ALARM 2 Calibration Adjustments by the following procedure:
1.Set RANGE Select in a position ap- propriate to the span standard gas.
2.Inject span standard gas through ana- lyzer at 50 to 500 cc/min.
3.Verify that ALARM 1 and ALARM 2 Deadband Adjustments (See Figure 3-1, page 3-3) are set for minimum value (turned fully counterclockwise). These potentiometers should be fac- tory-set for minimum deadband. Both potentiometers MUST REMAIN at this setting throughout calibration of the alarm setpoint adjustments.
4.Adjust ALARM 1 control function as follows:
a.With ALARM 1 Setpoint Adjust- ment at 100% (i.e., position 10 on dial), adjust front panel SPAN Control so that the display or re- corder reads exactly fullscale.
b.Set ALARM 1 Calibrate Adjust- ment (R63) to its clockwise limit.
