Archive for the ‘protection relays’ Category

Agreement to use DNO’s circuit breaker to protect User’s network

Thursday, April 8th, 2010

The agreement to allow the use of the DNO’s CB and/or the DNO’s protection relays and systems to protect the User’s network is based on reasonable endeavours by the DNO to accommodate the User’s needs. The agreement can be terminated by either party at any time. The DNO reserves the right to terminate the agreement should alterations to his network preclude the continued delivery of these services.

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The DNO will use reasonable endeavours to find new solutions for continuing to provide the services, but any costs will be charged on a T&M basis to the User.

Cost indicated as x, y, a, b, c, d, e, f would be specified individually by DNOs, possibly in accordance with a revised LC4 statement.

The DNO’s CB can be tripped by the User’s protection; on request from the User’s Control Person; or by the User directly via an emergency trip button. There will be no charge for these operations.

The DNO’s CB will not be used for synchronizing.

The DNO’s CB cannot be closed by the User. Should the User wish the DNO to energize the User’s system, this will be requested in the normal manner by the User’s Control Person.

There will be no charge for the first [] operational closes to energize the User’s system in any financial year. Subsequent closes will be charged at £[x] for closes by telecontrol and £[y] for closes by the DNO’s staff on site.

The DNO and the User may agree to implement an automatic reclosing system for the DNO’s CB. There will generally be no charges for operation of the CB under this system.

Exceptional Maintenance Costs
Any exceptional maintenance costs, such as post-fault maintenance of the DNO CB following the clearance of a fault on the User’s system, will be charged to the User on a T&M basis at £[z] per hour.

Isolation and Earthing
The DNO will provide an isolation and earthing service for the User’s network.

The DNO will attend to effect isolation and or earthing with [] days notice. The charge per attendance will be £[a] for the first hour or part thereof and £[b] for each subsequent hour or part therof.

For an unplanned event, the DNO will endeavour to attend within three hours. During exceptional event periods reasonable endeavours will apply. Attendance for unplanned events will be charged at £[c] per hour during the period 0830 to 1700 Monday to Friday, and £[d] at all other times.

The DNO will provide services for isolation and earthing as above for the purposes of facilitating the User’s need to test his circuits.

User’s Protection
The User’s Protection can trip the DNO’s CB.

The DNO and the User will agree as to the provision of DC supplies for the User’s protection. Where the DNO provides the DC supplies, the cost of the DC supplies will be shared on an equitable basis.

The User will be solely responsible for monitoring the health of the User’s trip circuit, including any parts of the circuit afforded by DNO equipment.

Co-ordination of Protection
In accordance with DPC4.4.4 the DNO and the User will agree the protection co-ordination arrangements, including specific faults on the User’s system that the DNOs protection will be relied upon to clear. The User will furnish the DNO with a schedule of these specific faults. The User will state for each specific fault if the DNO is required to ensure that the fault will also be protected by the DNO’s back up protection should the DNO’s interface CB fail to trip for any reason. The DNO shall describe the protection systems (including any backup systems) and the settings to be applied and the user shall then make an assessment as to whether the protection provided by the DNO equipment is adequate to meet their statutory obligations and commercial requirements The DNO will charge £[e] for each such protection assessment.

Limitation of DNO’s Liability
The DNO shall [have no liability/agree the liability] to the User for the failure of the DNOs CB, and/or backup protection and/or backup CB, to operate correctly to clear a fault on the User’s system.

The DNO shall [have no liability/agree the liability] for the failure of any DC supplies afforded by the DNO for the purpose of operating the User’s protection.

The DNO shall provide such information about the design, condition and operating characteristics of the DNO’s protection and CB as the User may from time to time request. This information will be collated by the DNO on a T&M basis at a charge of £[f] per hour. The DNO will provide an indicative estimate of the number of hours to collate the information on request