Page 14 of 190 Report No.: 6068396.50 TRF No. G99/1-4_V1.0 G99/1 Clause Requirement - Test Result - Remark Verdict 7.2.1 This refers to the frequent or long-term operation of Power Generating Modules in parallel with the Distribution Network. Unless otherwise stated, all sections in this EREC G99 are applicable to this mode of operation. P 7.3 Infrequent Short-Term Parallel Operation Long-Term Parallel Operation. N/A 7.3.1 This mode of operation typically enables Power Generating Modules to operate as a standby to the DNOs supply. A short-term parallel is required to maintain continuity of supply during changeover and to facilitate testing of the Power Generating Module.
N/A 7.3.2 In this mode of operation, parallel operation of the Power Generating Module and the Distribution Network will be infrequent and brief and under such conditions, it is considered acceptable to relax certain design requirements, such as protection requirements, that would be applicable to long-term parallel operation. The provisions of this Section 7 should also be read with Annex A.4 which details some other specific exclusions of parts of Sections 9 to 12 of this EREC G99.
N/A 7.3.3 As the design requirements for Power Generating Module operating in this mode are relaxed compared with those for long-term parallel operation, it is necessary for the DNO to specify a maximum frequency and duration of short-term parallel operation, to manage the risk associated with the relaxed design requirement. N/A 7.3.4 The following design variations from those in the remainder of this EREC G99 are appropriate for infrequent short-term parallel operation: N/A 7.3.5 Some Manufacturers have developed fast acting automatic transfer switches. These are devices that only make a parallel connection for a very short period of time, typically 100 – 200 ms.
Under these conditions installing conventional Interface Protection with an operating time of 500 ms is not appropriate when the parallel will normally be broken before the protection has a chance to operate. There is however the risk that the device will fail to operate correctly and therefore a timer should be installed to operate a conventional circuit breaker if the parallel remains on for more than 1 s. The switch should be inhibited from making a transfer to the DNO’s Distribution Network whilst voltage and frequency are outside expected limits. N/A 7.4 Switched Alternative-Only Operation Long-Term Parallel Operation.
N/A 7.5 Phase Balance of Type A Power Generating Module output at LV Type B C D Power Generating Modules. N/A