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Table 17 - jam settings, Undercurrent (load loss), Table 18 - undercurrent settings – Rockwell Automation 825-P Modular Protection System for Motors User Manual User Manual

Page 77: Jam undercurrent (load loss)

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Rockwell Automation Publication 825-UM004D-EN-P - November 2012

77

Configuring Protection & Logic Functions Chapter 6

Jam

When the motor is running, the relay offers jam detection. When the motor load
jams (stalling the motor), the phase current increases to near the locked rotor
value. When Load Jam Tripping is enabled, if the phase current exceeds the Load
Jam Trip Level setting for longer than the time delay setting, the relay trips. Set
the Load Jam Trip Level greater than the expected normal load current but less
than the rated locked rotor current. This setting is entered in per unit of the Full
Load Amps (

I

e

) setting.

Undercurrent (Load Loss)

Table 18 - Undercurrent Settings

The relay arms the load-loss detection logic after the motor starts, as defined by
the Undercurrent Start Inhibit time delay setting. Set this delay to allow pumps or
compressors to reach normal load. Once armed, this function issues a warning or
trip if phase current drops below warn or trip level for the specified time delay.

Set the Undercurrent Trip and Warn Levels greater than the expected motor no
load current, but less than the minimum current expected when the motor is
operating normally. These settings are entered in per unit of the Full Load Amps
(

I

e

) setting.

If you expect the motor to normally operate at no load, disable the Trip and Warn
elements. The relay automatically hides the associated time delay settings.

Table 17 - Jam Settings

Setting Prompt

Setting Range

Factory Default

JAM TRIP LEVEL

Off, 1.00…6.00 x

I

e

Off

JAM TRIP DELAY

0.0…120.0 s

5.0

JAM WARN LEVEL

Off, 1.00…6.00 x

I

e

Off

JAM WARN DELAY

0.0…120.0 s

10.0

Setting Prompt

Setting Range

Factory Default

UC TRIP LEVEL

Off, 0.10…1.00 x

I

e

Off

UC TRIP DELAY

0.0…120.0 s

5.0

UC WARN LEVEL

Off, 0.10…1.00 x

I

e

Off

UC WARN DELAY

0.0…120.0 s

10.0

UC START INHIBIT

0…1500 s

0