GE Industrial Solutions DV-300 DC Drive Users Manual - Manual (Page 39)

DV-300 Adjustable Speed Drives
——— DESCRIPTION, COMPONENT IDENTIFICATION AND SPECIFICATIONS ———
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2.7 MOTORS, ENCODER, TAChOMETER
The converters of the DV-300 series are provided for the regulation of DC motors with an independent excitation.
As for speed feedback there is the use of a sinusoidal incremental encoder, a digital encoder or an analog tachometer
generator. In case of limited precision needs it is possible to use as feedback the armature voltage without defluxing.
2.7.1 Motors
The electrical and mechanical data of the dc motors with an independent excitation refer to a particular function-
ing field. The following points have to be taken into consideration in order to operate these motors:
Motor data necessary to connect it to a converter
The data on the motor nameplate:
- Armature rated voltage
- Armature rated current
- Field rated current
- Motor rated speed
Motor protection
Thermo relay of the motor
- The relay contact can stop the drive through a control circuit or it can signal to the converter as an external
failure (terminal 15).
N
ote
!
Remember that with a thermo relay it is possible only to control the heating of the motor due
to an overload, but not the one due to an insufficient ventilation. For this purpose some PTC
thermistors or thermal switches should be inserted in the motor windings.
Thermistors and thermal switches
On terminals 78 and 79 it is possible to connect a thermistor or thermal switch in order to detect motor overheat-
ing. When no temperature sensors are present an external resistor (R = 1 kohm) has to be connected to these
terminals. The connection of the sensor has to be done according the following instructions.
Thermistors (PTC)
PTC thermistors according to DIN 44081 or 44082 fitted in the motor can be connected directly to the converter vie
terminals 78 and 79. In this case the resistor ( 1 kohm) mounted between the terminals 78, 79 has to be removed.
Thermal switches (klixons) in the motor windings
Temperature-dependent contacts “klixon” type can disconnect the drive via the external control or can be reported as an
external error on the converter (terminal 15). They can also be connected to the terminals 78 and 79 in order to have a
specific error signal. In this case remove the 1 kohm resistor from these terminals and connect it in series to the wiring.
Limitation of the converter current
The current limitation can protect the motor from unwanted overloads. To this purpose it is necessary to set
the current limitation and the control function of the converter overload (overload function), so that the current
remains within the values allowed for the motor.
n
ote
! Remember that with a current limitation it is possible to control only the motor heating due
to an overload, but not the one due to an insufficient ventilation. For this purpose some PTC
thermistors or thermal switches should be inserted in the motor windings.