Datasheet

Page 8
www.sensata.com
Copyright © 2018 Sensata Technologies, Inc.
Motor Overload Protection
The thermal load of the motor is calculated using a thermal model (see Thermal Overload Protection Curves). The nominal motor current Ie can be
adjusted via a potentiometer on the front. To calculate the thermal load the current is measured in phase T3.
A symmetrical load current in all 3 phases of the motor is assumed for flawless operation. When the trigger value, stored in the trigger character-
istics, is reached, the motor is switched off and the device switches to fault 8. The fault can be acknowledged via the front Reset button or via the
external Reset input.
IMPORTANT: The data of the thermal model can be cleared through a Reset or by removing power to the unit. In this case, the user must provide
adequate cooling time to the motor.
Phase Failure Detection
To make sure the motor is not asymmetrically loaded a check takes place during the motor start to determine if phases L1, L2 and L3 are present. If
one or several phases are absent then the device switches to fault 4. The fault can be acknowledged via the Reset button or via the external Reset
input.
Mains Isolating Relay (only for model DRMS48D93)
In the off state or when a fault condition is detected the motor terminals are isolated from the mains voltage by a 4-pole forcibly guided contact
relay. The contact opening is min. 0.5 mm.
IMPORTANT: Do not remove the 24 VDC auxiliary supply voltage while the output is under load. Failure to do so can cause a permanent damage to
the mains isolating Relay.
Signalling Output Relay
Contact 11/14 is closed if no fault is present on the device.
Reset Function
There are 2 options available to acknowledge a fault condition:
Front Reset button:
Acknowledgement is done by momentarily pressing the Reset button at the front of the device. If the button is still pressed after 2 seconds the
device resumes the fault state.
Remote Reset input:
Remote acknowledgement can be accomplished by connecting an external switch (Normally Open) between terminals MAN and RES. Acknowledge-
ment is triggered as soon as this external contact closes. If the contact is still actuated after 2 seconds the device resumes the fault state since a
defect in the acknowledgement circuit cannot be ruled out.
DIMENSIONS
DRMS48D91
± 0.02 in / 0.5 mm.
All dimensions are in: in [mm]
INPUT TERMINAL SLOT
SCREW (12 PLACES)
OUTPUT TERMINAL SLOT
SCREW (6 PLACES)