UL 1778:2017 pdf free download – STANDARD FOR SAFETY Uninterruptible Power Systems.
2.6.3.4 Resistance of earthing conductors and their terminations Replace item b) of the RD with the following:
b) For equipment powered an AC MAINS SUPPLY, if the PROTECTIVE CURRENT RATING of the circuit under
test exceeds 16 A, the test current is 200% of the PROTECTIVE CURRENT RATING, up to a maximum test current of 500 A, and the duration of the test is as shown in Table 2E.
Additional subcla use:
2.6.101 Bonding
For Class I PLUGGABLE EQUIPMENT TYPE A, the UPS shall provide sufficient terminals, earthed socket-outlets, or other means to permit, in the final installed system configuration, equipotential protective bonding to the UPS from other Class I equipment, including external UPS battery cabinets, irrespective of whether the UPS primary protective conductor is disconnected from its source. Any special bonding instructions shall be stated in the user’s instructions.
Refer to Annex EEE for grounding supplied from separately derived a.c. sources.
A UPS having a separately derived output that is intended to be grounded in the field shall be marked with the following or equivalent words:
“The output a.c. circuit is considered as a separately derived source”.
If local codes require grounding of this circuit, use terminal (identify terminal) for bonding this circuit to the ENCLOSURE. Ground the ENCLOSURE to a suitable grounding electrode in accordance with local code requirements.
2.7 Overcurrent and earth fault protection in primary circuits
2.7.1 Basic requirements
Additional paragraphs:
For components in series with the AC MAINS SUPPLY to the equipment, such as the supply cord, appliance coupler, EMI filter, and switch, short-circuit and earth fault protection may be provided by protective devices in the building installation. See Annex LLL.
AC output overcurrent protection shall be provided. Overcurrent protection need not be provided for permanently connected equipment when the overcurrent protection is provided by others in the final installation.
If reliance is placed on protection in the building installation, the installation instructions shall comply with 2.7.1/RD, except that for PLUGGABLE EQUIPMENT TYPE A, the buildings installation shall be regarded as providing protection in accordance with the rating of the wall outlet, and 2.7.1/RD does not apply.
NOTE: Building overcurrent protection is an acceptable method for protecting PLUGGABLE TYPE A UPS.
If the protection against electric shock of the UPS (see 2.1) relies on residual current devices in the building installation circuit and the design of the UPS is such that in any normal or abnormal operating condition a fault current to earth with d.c. component is possible, the installation instructions shall define (an) appropriate building residual current device(s).
Compliance is checked by inspection and functional test.
Additional subcla use:
2.7.101 Battery supply circuit overcurrent protection
A battery supply circuit shall be provided with overcurrent and short-circuit protection as follows:
Where the batteries are installed inside the UPS, the battery supply circuit shall be provided with a protective device located adjacent to the battery connecting means before any component that may fail short-circuited, such as capacitors, solid-state devices, or similar components.
Where the batteries are installed outside the UPS, the location of the overcurrent-protective device shall be as indicated above, within the separate cabinet.
The rating of the overcurrent-protective device located internally shall be such as to protect against conditions described in 5.3/RD.