Guidelines For Setting Trend Alarms - GE Hydran 201i Instruction Manual

1.1.1.6 Hourly Trend
The hourly trend alarm uses the following parameters:
• HourTrAlr H and HourTrAlr HH: Hourly trend High and High-High alarm set
points.
• HourTrAlr Delay: The hourly trend alarm delay determines the period of time
during which the hourly trend must exceed the corresponding High and High-
High alarm set points in order to trigger the alarm. Accordingly, the hourly
trend must get below the alarm set point for the same amount of time in order
to cancel the alarm. This delay is set in percentage of the period of the hourly
trend computation.
• HourlyTr Period: The period of time (in hours) during which the hourly trend is
calculated. Increasing the period decreases the normal fluctuations of the
readings, but increases the response time.
The readings of the Hydran 201i System should be monitored over a minimum period
of two weeks before setting these parameters; follow the same rules as for the gas High
alarm (see Section 1.1.1.5).
1.1.1.7 Daily Trend
The daily trend alarm uses the following parameters:
• DayTrAlr H and DayTrAlr HH: Daily trend High and High-High alarm set
points.
• DayTrAlr Delay: The daily trend alarm delay determines the period of time
during which the daily trend must exceed the corresponding High and High-
High alarm set points in order to trigger the alarm. Accordingly, the daily
trend must get below the alarm set point for the same amount of time in order
to cancel the alarm. This delay is set in percentage of the period of the daily
trend computation.
• DailyTr Period: The period of time (in days) during which the daily trend is
calculated. Increasing the period decreases the normal fluctuations of the
readings, but increases the response time.
The readings of the Hydran 201i System should be monitored over a minimum period
of two months before setting these parameters; follow the same rules as for the gas
High alarm (see Section 1.1.1.5).

11.4.2 Guidelines for Setting Trend Alarms

The hourly and daily trend High and High-High alarm settings cannot be described in
terms of absolute criteria. They are related to the user's field experience and the utility's
standard practice.
Page 164
Hydran* 201i Instruction Manual
MA-033 Rev. 14.0, 12-Nov-18