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Diode Failure Detector

The Stamford Diode Failure Detector senses ripple current in the exciter output to provide indication of a failed diode in generators. It has a delayed response to avoid false trips and indicates faults through voltage free contacts. It allows generators to continue operating until a planned shutdown for diode replacement.

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Islam Alazb
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401 views2 pages

Diode Failure Detector

The Stamford Diode Failure Detector senses ripple current in the exciter output to provide indication of a failed diode in generators. It has a delayed response to avoid false trips and indicates faults through voltage free contacts. It allows generators to continue operating until a planned shutdown for diode replacement.

Uploaded by

Islam Alazb
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Diode Failure Detector

The Stamford Diode Failure Detector (DFD) is suitable for use


with all Stamford Generators. It senses the level of ripple
current in the exciter output to provide indication of a failed
diode, either short or open circuit.
Frequently demanded in the oil and gas industries this
warning device is increasingly required by many other users
who recognise the benefits of early failure warning. The DFD
has a delayed response of 7 seconds to avoid nuisance trip
signals before indicating the fault via voltage free changeover
contacts.
By receiving a quick warning of a single failed diode the user
may arrange shutdown (manually or automatically) of the
engine. Alternatively on receipt of the warning, the exciter
field current or voltage can be monitored, reducing load if
necessary, to ensure that recommended levels are not
exceeded. In this way the generator set can continue to
provide emergency supplies until a planned controlled
shutdown when the necessary diode replacements can be
made.
Of course a Stamford Series 3 separately excited system
offers the safety of over-excitation protection within the AVR.
But the DFD actually diagnoses if the fault lies with the
rectifier diodes, and so encourages the best course of action.

Reliable solid-state warning of rotating rectifier diode


failure.

Jumper Selectable D.C. (12 or 24V) or AC (120 to 240V).

Simple connections to generator.

Simple test facility.

TECHNICAL SPECIFICATION
Supply voltage

DC 12 - 28V
AC 100 140V
Or 200 280V

Supply current

DC 0.2A max

Output

Voltage Free Contacts


Isolation 2kV
1 Pole Changeover
Rating 5A @ 30Vdc/240ac

Response time

(Approx) 7 seconds

ENVIRONMENTAL
Operating temp
Storage temp
Humidity
Vibration

- 40C to + 70C
- 55C to + 80C
0 to 60C 95%RH
20 100 Hz 30mm/seconds
100 Hz 2kHz 2.0g

Not suitable for mounting in generator terminal box.


Switchboard or bedplate mounting recommended.

Barnack Road Stamford Lincolnshire PE9 2NB


Tel: 00 44 (0)1780 484000 Fax: 00 44 (0)1780 484100

2006

TD_DFD_GB_07.05_01

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