The Compact ASXP Current Relay is a Versatile Option for Single and Three-Phase Motor Monitoring

The ASXP series current relay provides control engineers with features to help solve motor maintenance requirements for both single phase and three-phase motors.

Use the ASXP to monitor the load of a grinder drive motor, and when the grinder is working properly, the contact interlocks the in-feed drive. This allows the in-feed to be halted when the grinder is over loaded.

Use the ASXP to monitor the load of a grinder drive motor, and when the grinder is working properly, the contact interlocks the in-feed drive. This allows the in-feed to be halted when the grinder is over loaded.

A set delay of two seconds before the output relay closes allows the motor current inrush to occur without tripping the output contact in most applications. After the motor is running, a separate adjustable delay on current increase allows the sensor to “ride through” short duration overloads. Overloads that are not long enough to cause damage to the motor windings but can cause standard current operated switches to trip occur often in grinding and cutting processes. Both the current trip point and run delay are field adjustable using a single turn potentiometer conveniently mounted on the top of the sensor. The exact current magnitude can be set before or after installation, along with the time delay before the output relay energizes. Setting the adjustments before installation is easier and safer than doing so inside the confined space of a motor control center bucket or a component rich control panel.

The electromechanical single pole, double-throw relay output is rated to control up to one amp at 120 VAC and two amps up to 30 VDC. This capacity allows the sensor to be used to control NEMA size 1 contactor coils or other inductive loads without concern. The contact can also be used to provide input to a programmable controller or distributed control system with zero off state leakage (often seen with some manufacturer’s solid-state output “contacts”).

ASXP_app_note_0712-chart

APPLICATION: MOTOR PROTECTION

  • Serves as an electronic proof-of-operation; detects current draw changes in motors when they encounter problems such as pumps running dry or impending bearing failure
  • Non-intrusive, less expensive to install than differential pressure flow sensors or thermal switches
  • Much quicker response time than Class 10 overload relays
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