Littelfuse T7900 User Manual

Generator Control

Basic

T7900 SERIES

Electronic Potentiometer

Simplified Circuit Diagram

Description

The T7900 Electronic Potentiometer is used as converter
between pulse contacts and a device requiring control
adjustment by a voltage or current signal, such as an
electronic speed controller. The T7900 acts in a similar
manner to a motorized potentiometer, except that the
outputs are a voltage, a current or a pulse width modulated
signal (PWM), while the motorized potentiometer has a
variable resistor output.

In generator control applications, the T7900 can be used
together with a Synchronizer and a Load Sharer. The T7900
converts the increase and decrease pulses of these modules
into a suitable analog voltage, current or PWM signal. This
analog output signal can be used as a control input to the
electronic speed controller.

SUPPLY

24 Vdc/Vac

+ –

RESET

POWER REF.

IN1 IN2

REF

IN3 INCR REF DEC

T7900

(Electronic Potentiometer)

0-10 V REF

Optional

AC Supply

L

1

L

2

±10 V 0-20 mA

Ordering Information

ORDERING NUMBER

T7900.0010 24 Vdc/Vac

T7900.0030 250 Vac

TERMINALS

11-12 1-3

PWM

Features & Benefits

FEATURES BENEFITS

Wide selection of output
ranges including PWM

Independent ramp-up &
ramp-down time setting

Power reference function

Available with Vac supply

Visual indication of
increase/decrease signals

DIN-rail or screw­mount & adjustment by
potentiometers

Ensures possible use with a broad variety of
speed governors and voltage regulators

Provides optimum controlabilty of speed
governors and voltage regulators regardless of
generator size

Enables alternative use as power reference
unit providing generator load set point in grid
parallel installations

Enables direct supply from installation

Provides quick and concise status information

Easy installation

Specifications

Supply 8-36 Vdc/ Vac
Consumption Max. 120 mA at 24 Vdc
Output Ranges –10 V-+10 V (or any part of this, e.g. 0 V-+1 V)

0-20 mA (or any par t this, e.g. 4 mA-20 mA)
0-100% PWM 500 Hz (or any part of this e.g. 10-90%)
0-100% PWM 2.94 MHz (or any part of this
e.g. 10%- 90%)
PWM Output Signal Frequency: 500 Hz of 2,94 KHz. Level: 0-10 V
Default reference: 50%

Operating
Temperature –20°C to +70°C
EMC EN50263
Burn-in 50 hours before final test
Enclosure Material Polycarbonate. Flame retardant
Weight 0.3 kg for T 7900-00, 0.5 kg for other types
Dimensions H 70 mm (2.7“); W 100 mm (3.9“);
D 115 mm (4.5“)
Installation 35 mm DIN rail or 4 mm (

3

/16”) screws

© 2013 Littelfuse Protection Relays & Controls
www.littelfuse.com/t7900

Rev: 4-A-050313