Woodward MFR300-75M 8444-1107 8444-1108 8444-1109

Woodward  MFR300-75M 8444-1107   8444-1108  8444-1109

General notes

df/dt (rate of change of frequency) monitoring measures the stability of the frequency.

The frequency of a source will vary due to changing loads and other effects. The rate of

these frequency changes due to the load variances is relatively high compared to those of

a large network

Voltage Increase

General notes

Voltage is monitored depending on parameter “Monitoring” (parameter ╚═▷ 8806). This

function allows the monitoring of the voltage quality over a longer time period. It is

realized as a 10 minute moving average. The function is only active, if the frequency is

larger than 60 % of the nominal frequency. If “Voltage measuring” (parameter ╚═▷ 1851)

is configured to a three-phase measurement, the slow voltage increase alarm is

monitoring the individual three-phase voltages according to parameter “AND

characteristics” (parameter ╚═▷ 8849).

QV Monitoring

General notes

In case of undervoltage some grid codes require a special monitoring function to avoid

the import of inductive reactive power at the interchange point. The QV monitoring is a

function of voltage and reactive power. To prevent malfunction, a “Minimum current”

(parameter ╚═▷ 3287) must be configured.

QV monitoring is triggered if the following conditions are fulfilled: (Refer to ╚═▷ Fig. 39 for

details)

QV monitoring is configured to “On” (parameter ╚═▷ 3292)

Measured reactive power is higher than the configured “Reactive power threshold”

(parameter ╚═▷ 3291)

Measured average current is higher than the configured “Minimum current”

(parameter ╚═▷ 3287)

Measured voltages are below the configured “Limit undervoltage” (parameter ╚═▷

3285)

As a result Timer 1 and Timer 2 are starting. If the delay time “Delay step 1” (parameter

╚═▷ 3283) has exceeded, the specified relay for step 1 is energized. If the delay time

“Delay step 2” (parameter ╚═▷ 3284) has exceeded, the specified relay for step 2 is

energized

Overcurrent (Level 1. 2 & 3) ANSI# 50/51

General notes

Current is monitored according to how the parameter “Current measuring”

(parameter ╚═▷ 1850) is configured. This controller provides the user with three definite

time alarm levels for overcurrent faults.

Monitoring of the maximum phase current is performed in three steps. Every step can be

provided with a delay time independent of the other steps

Ground Fault (Level 1 & 2)

Calculated ground fault

The current is monitored depending on how parameter “Current measuring” (parameter

╚═▷ 1850) is configured. The measured three conductor currents IL1. IL2 and IL3 are

vectorially totaled (IS = IL1 + IL2 + IL3) and compared with the configured fault limit (the

calculated actual value is indicated in the configuration software). If the measured value

exceeds the fault threshold limit, the configured relay is energized.