Alarm Setup

 

The 9215 controller can be configured to use three (3) different alarms. Each of the alarms consists of an alarm setpoint, alarm source, alarm type, alarm hysteresis, smart alarm, ON delay time, and a 0 SP blocks alarm value. The alarms come from the factory with a default configuration dependent on the application but also can be modified prior to shipment to your facility or in the field by a supervisor. See the section Appendix D – Factory Default Settings for the 9215 Controller for more information on factory default settings for the alarms.

 

Setpoint

This value is the setpoint for the alarm.  Clicking on this value will display an input box from which the user can select a new value.  The range is from
–32767 to 32767.

 

 

Alarm Type

This value is the type of alarm used.  Options are:

  • Process High

  • Process Low

  • Band, Normally Open

  • Band, Normally Closed

  • Deviation, Normally Open

  • Deviation, Normally Closed

 

These alarm types are described in more detail below:

 

A process high alarm is active when the alarm source is greater than the alarm setpoint. A process low alarm is active when the alarm source is less than the alarm setpoint. Band and deviation alarms apply to sources that are the process variable of a control loop. They compare the control loop process variable minus the control loop setpoint to the   alarm setpoint.  The control loop process variable minus the control loop setpoint is called the deviation.

 

For a band alarm the absolute value of the deviation is compared to the alarm setpoint. For a band Normally open, the alarm is active if the absolute value of the deviation is greater than the alarm setpoint. For a band Normally closed, the alarm is active if the absolute value of the deviation is less than the alarm setpoint.

 

If the alarm setpoint for a deviation alarm is positive, then only a positive deviation  is tested for the alarm.  Likewise, if the alarm setpoint is negative only a negative setpoint is tested for the alarm.

A deviation, normally open alarm is active if the deviation is greater than the alarm setpoint in the direction of the alarm setpoint sign. A deviation, normally closed alarm is active until the deviation is greater than the  alarm setpoint in the direction of the alarm setpoint sign.

 

Hysteresis

This value is the Hysteresis value.  The Hysteresis is a set number that works with the alarm to help control a motor or pump longer to reach a set amount to come back into band before it will shut off motor or pump.

 

Example: Using quench oil as an example, suppose the SP is 200 °F.  The alarm is set as a deviation of +10 °F.   At 210 °F, the alarm is active and the pump will run to cool the oil.  With a hysteresis of 8 °F, the alarm and pump will turn off at 202 °F.   It will turn back on when it is 10 °F above setpoint.  If the setpoint is still 200 °F, then at 210 °F, it will turn on again.

 

Clicking on this value will display an input box from which the user can select a new value.  The range is from -32767 to 32767.

 

Smart Alarm

This value is a display of the Smart Alarm status.  A smart alarm is an alarm that works with a Process Variable (PV), and, when enabled, it will not be active until the PV is within band of the setpoint. The alarm sounding - if active - will be disabled until within the SP band. When it is in band, the alarm will go active unless on delay time is set.

 

Example:  If the SP is 1700 °F and the band is 10 °F, the alarm will not be active until the PV reaches 1690 °F.  The value can be either disabled or enabled.

 

ON Delay Time

This value is the On Delay Time for the alarm.  Clicking on this value will display an input box from which the user can select a new value.  The range is from -32767 to 32767.

 

0 SP blocks alarms

This value will allow a 0 setpoint to block an alarm.  The options are either No or Yes.

 

 

BO/Impedance inhibits alarm

If BO/Impedance inhibits alarm is turned to Yes, no alarm will sound if the carbon percentage drops because of a burnoff.

 

Inhibit source

Alarms can be inhibited in order to prevent false or unnecessary alarm notifications. The Inhibit Source option will allow the user to set the source of the inhibit signal. The options are: None, Input 1 – Input 4,Soak timer inactive (The alarm will not happen if the furnace is in a soak if this option is selected), and Input 6 – Input 15.

 

Disable on open input

An alarm can be disabled when an input the open in order to avoid false or unnecessary alarms. This option will allow the user to specify if the alarm is disabled when the input is open.  The options are either no or yes. This option is only valid for alarms with input sources.

 

Disable on open input

An alarm can be disabled when an input the open in order to avoid false or unnecessary alarms. This option will allow the user to specify if the alarm is disabled when the input is open.  The options are either no or yes.

 

Base Setpoint

This applies only if the alarm source is DA, KN, Super KN, %C, %O2, KC, or KO. Since these sources are not associated with a control loop, there is not a control loop setpoint to use with the band or deviation alarm types. This value will be used as the target setpoint for those alarm types.

 

The Return button will return the user to the menu screen.