Alarm Setup

 

 

The 9120 controller can be configured to use three different alarms. Each of the alarms consists of an alarm setpoint, alarm source, alarm type, hysteresis, smart alarm, alarm on delay time, and a zero 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.  Press the alarm dropdown menu to choose between them. 

 

Setpoint

This value is the setpoint for the alarm.  The range is from –32767 to 32767.

 

Alarm Source

This value is the source of alarms used. 

The options are:

PV 1 Value

PV 2 Value

PV 3 Value

Input 1 Value

Input 2 Value

Input 3 Value

Percent output 1 Value

Percent output 2 Value

Percent output 3 Value

 

Alarm Type

This value is the type of alarms used.

The options are:

Process High

Process Low

Band, Normally Open

Band, Normally Closed

Deviation, Normally Open

Deviation, Normally Closed

 

Deviation alarm is single sided.  i.e. a +10 deviation will alarm when the PV is greater than SP + 10 but not neg.  A -10 deviation will alarm when the PV is less than SP -10 but not on the positive side.

 

The actual relay setup with that alarm will only energize depending on the setpoint. For the standard alarms (1, 2, and 3), the user can select if the alarm condition is for above or below.  This will dictate when the relay will energize.

 

Example: alarm 1 set to plus 10F will alarm 11 degrees above setpoint and pull in the relay.  It will show alarm 10 degrees below but not pull in the relay.

 

A Band alarm will activate and energize the relay on both sides (+) and (-).

 

Note - some alarm types may be fixed at the current value.

 

Hysteresis

The hysteresis is in degrees, i.e. 10 hysteresis = 10 degrees.

Alarm hysteresis should not have a decimal place. It is in units. If it is a control loop doing on/off control then the decimal place on the reset (hysteresis) should be ignored. 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, assume the SP is 200F.  The alarm is set as a deviation of +10F.   At 210 the alarm is active and the pump will run to cool the oil.  With a hysteresis of 8 degrees the alarm and pump will turn off at 202F.   It will turn back on when it is 10 degrees above setpoint.  If the setpoint is still 200 then at 210 it is 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 and when enabled it will not be active until the process variable is within band of the setpoint.

 

Example:  If the SP is 1700 and the band is 10 degrees the alarm will not be active until the PV reaches 1690.

 

The value can be either Yes or No.

 

Alarm on delay time

This value is the on Delay Time for the Smart Alarm, in seconds. If the timer is utilized the alarm will not be active until in band and the timer has timed out (this is in seconds).

 

Example: If you select 30, the output will not energize until 30 seconds after the alarm is active.

Clicking on this value will display an input box from which the user can select a new value. 

 

Note – This value is fixed at No for Alarm 1.

 

The range is from -32767 to 32767 seconds. 

 

Zero SP Blocks Alarm

This value will allow a 0 setpoint to block an alarm.  Note – This value is fixed at No for Alarm 1.  The options are either No or Yes.  Note – Setting this value to Yes will force the Smart Alarm value to be set to No