SSD 605C Product Manual - page 100

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Programming Your Application

605C Frequency Inverter

I*t TRIP

This function block is designed to protect

the motor and the Inverter from damage

that may be caused by continuous operation

beyond specification.

Functional Description

The I*t UPPER LIMIT, I*t THRESHOLD and I*t TIME parameters effectively define how

long the output current may exceed the I*t THRESHOLD . For example, if the output current

equals the I*t UPPER LIMIT then the trip will occur after I*t TIME . Alternatively, if the output

current exceeds the I*t THRESHOLD by only half as much as the I*t UPPER LIMIT then the

trip will occur after twice the I*t TIME .

As the output current is constantly monitored by the Inverter the I*t TRIP block constantly

updates the time at which a trip might occur, taking into account not only the present output

level but also the recent history. For an output current that moves around the I*t THRESHOLD

level, the time for which the current is below the level is used to balance the time for which the

current is above the level. This avoids spurious trips while maintaining the monitoring function.

Refer to Chapter 7 for a description of the trips supported by the Inverter.

MMI Menu Map

1 SETUP PARAMETERS

2 FUNCTION BLOCKS

3 TRIPS

4 I*T TRIP

I*T THRESHOLD

I*T TIME

I*T UPPER LIMIT

I*t TRIP

105.00 % – [237] I*t THRESHOLD

–

60 s – [238] I*t TIME

–

150.00 % – [239] I*t UPPER LIMIT

–

Parameter Descriptions

I*t THRESHOLD

Range: 50.00 to 105.00 %

If the magnitude of the current delivered by the Inverter is greater than this threshold then the

Inverter will trip after a time determined by I*t TIME and I*t UPPER LIMIT .

This parameter must be less than the I*t UPPER LIMIT .

I*t TIME

Range: 5 to 60 s

The trip delay time for a constant output current equivalent toI*t UPPER LIMIT .

I*t UPPER LIMIT

Range: 50.00 to 150.00 %

The output current level used to determine the trip delay. Used in conjunction with I*t TIME .

This parameter must be greater than I*t THRESHOLD .

Time

Current

Area that defines how

long the output may

exceed the threshold.

Example of current

output that causes

a trip.

Upper limit

Threshold

I*t TIME