Download AT-6000 GDS Ground Fault Detection System

Accumetrics, Inc.: A PCB Group Company
AT-6000 GDS Ground Fault Detection System
Field ground fault monitoring for synchronous generators/ brushless excitation
using digital telemetry
Optional 3 Foot Coaxial Extension Cable
(Not shown)
Receiver Output Cable
(Typically 36 feet long)
Receiver
Field Negative
and Rotor Ground
Input Leads
BS60007 configured transmitter
Transmitter
(Mounts on rotating diode
wheel of generator)
Alarm Panel with
Integral Power Supply
Copper Pipe Pickup Loop with 3 or 4 Foot Coaxial Cable
(The phenolic base is 1.3125 x 0.3125 x 1.0”
BS60009 “paddle style” receiver
Accumetrics developed the GDS for use with large, turbine-driven synchronous generators.
The system detects the occurrence of ground fault leakage current between the generator
field circuit and rotor ground, and transmits a good/bad fault determination (based upon a
fixed leakage current threshold) from the rotor transmitter to the non-rotating receiver.
Note: Although the AT-6000 is available, the newer Accumetrics AT-8000, and AT-8300
products are recommended as an upgrade path. These provide ground fault alarms and
valuable trending information based on the resistance of the fault, and are not sensitive to
the fault location voltage. Contact Accumetrics for information on these.
The AT-6000 GDS system uses a wireless inductive coupling technique to convey electrical
power to the rotor and transmit data off the rotor. It provides reliable transmission of data
which is unaffected by electrical noise, dirt, or contamination. During normal operation,
power to operate the transmitter circuitry is transferred from the stationary antenna loop as
a radio frequency.
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BT60010 configured transmitter
With a copper tubing pickup loop, the Ground Detection system operates under any machine condition; it does not require the generator to
be rotating or the field excitation to be activated. The transmitter auxiliary signal monitoring circuit provides a communications interface for
a discrete signal from a rotor-mounted electronic module, such as a diode fault detector, and transmits this signal off the rotor to the
stationary receiver. The paddle style receiver design requires rotor RPM for operation. The AT-6000 series has been provided to OEM’s and
end users since 1999.
visit us at www.accumetrix.com
6 British American Boulevard Suite 103-F, Latham, NY 12110
[email protected]
518-393-2200
ACCUMETRICS
A PCB GROUP COMPANY
Accumetrics, Inc.: A PCB Group Company
Ground Fault Detection Method
The rotating transmitter module contains circuitry capable of detecting the occurrence of a ground fault condition. The ground fault
condition is defined as an electrical leakage path modeled as a resistor RL which may exist from any point along the field winding
to the rotor ground. An effective ground fault detector must respond to ground faults at any location on the field winding. The ground
fault detection circuitry makes an electrical connection between the rotor ground and the negative side of the field, introducing a
small DC voltage that elevates the negative side of the field above ground. In this manner, a current will flow through RL even when
the ground fault exists in the negative terminal of the field. This current is measured within the ground detector and activates a
ground alarm if the current exceeds a fixed threshold.
Specifications
Mechanical requirements
Rotor Axial Growth
25.4 mm span
Radial Gap
15 mm nominal
Ambient Temperature
transmitter/antenna: -40 to 70 °C
power supply/receiver: 0 to 70 °C
Minimum threshold for detection
60 kOhms typical
Bias voltage
12 V typical
Signal levels
0 V low, 24 V high
System malfunction
Alarm = high
Ground fault alarm
Alarm = low
Auxiliary system
Alarm = low
Input current for detection
1 mA min., 40 mA maximum @ 70 °C
Input type
Optically isolated current input
Voltage
120 VAC/240 VAC 50/60 Hz
Watts
50 W maximum
Ground Fault Detection
Signal Output
Auxiliary input
Power requirements
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Benefits
RL
Rotor
Accumetrics offers these advantages
over conventional technology:
n
n
n
n
n
Ground
Fault
Generator
Field
Exciter
Wireless data transmission
Unaffected by noise, dirt, or contamination
Self-checking device for data accuracy
Proven design
Auxiliary motor input
+
-
VBIAS
A
3-12 V
Ground Fault Detector
ACCUMETRICS
About Accumetrics:
A PCB GROUP COMPANY
6 British American Boulevard Suite 103-F, Latham, NY 12110
Phone 518-393-2200
Fax 716-684-0987 n Email [email protected]
Website www.accumetrix.com
Founded in 1991, and a part of PCB Group (2013), Accumetrics is a world
leader in rotor telemetry, pioneering in every phase of rotor telemetry,
from quickly applied single channel dependable torque systems to
advanced aerospace systems with hundreds of high bandwidth
channels. No matter your industry or what your telemetry requirement,
chances are we can provide a system that will meet your needs.
© 2014 PCB Group, Inc. In the interest of constant product improvement, specifications are subject to
change without notice. PCB, ECHO, ICP, Modally Tuned, Spindler, Swiveler and TORKDISC are registered
trademarks of PCB Group. SoundTrack LXT, Spark and Blaze are registered trademarks of PCB Piezotronics.
SensorLine is a service mark of PCB Group. All other trademarks are property of their respective owners.
visit us online at www.accumetrix.com
Accumetrics-AT6000-0715
Printed in U.S.A.
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