(1) Description of Operation 7SR224
©2009 Siemens Protection Devices Limited Page 7 of 66
Section 1: Introduction
This manual is applicable to the following relays:
• 7SR224 Directional Overcurrent and Directional Earth Fault Recloser Control Relay
The 7SR224 relay integrates the protection and control elements required to provide a complete
recloser control relay.
The ‘Ordering Options’ Tables summarise the features available in each model
General Safety Precautions
1.1 CURRENT TRANSFORMER CIRCUITS
The secondary circuit of a live CT must not be open circuited. Non-observance of this precaution can
result in injury to personnel or damage to equipment.
1.2 EXTERNAL RESISTORS
Where external resistors are fitted to relays, these may present a danger of electric shock or burns, if
touched.
1.3 FIBRE OPTIC COMMUNICATION
Where fibre optic communication devices are fitted, these should not be viewed directly. Optical
power meters should be used to determine the operation or signal level of the device.
1.4 FRONT COVER
The front cover provides additional securing of the relay element within the case. The relay cover
should be in place during normal operating conditions.
1.5 FRONT FASCIA
For safety reasons the following symbols are displayed on the fascia
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