DLm touch current compliance
This section provides an overview of DLm touch current compliance.
DLm is designated as a fixed (stationary) electrical equipment with high earth-leakage
markings. Connect the cabinets to the AC supply with the recommended rated current
breakers and the attached cables. The "DLm power requirement" sections for
DLm8500 with Data Domain (DLm power requirements on page 31) and DLm8500
with PowerMax (DLm power requirements on page 38) provide details of the
recommended circuit breaker ratings. These recommended breaker ratings are based
on the maximum kW loading of the cabinet and not on the kVA figures of a particular
configuration. The kVA values listed in this manual are intended for air conditioning
and utility loading purposes only. The "Power and cooling data" sections for DLm8500
with Data Domain (Power and cooling data on page 32) and DLm8500 with PowerMax
(Power and cooling data on page 39) contain detailed information.
CAUTION Do not connect the DLm VTEC cabinet power supplies on separate
Main and Auxiliary circuit panels to differential trip devices. These devices are
typically called Ground Fault Circuit Interrupter (GFCI), Ground Fault Interrupter
(GFI), Earth Leakage Circuit Breaker (ELCB), or Residual Current Circuit
Breakers.
Because DLm systems are high earth-leakage devices, differential trip devices
(typically 30 mA) are not recommended due to random activation during utility feed
distortions and power line transients interacting with the cabinet noise filters. These
differential devices have trip ratings of 5 mA to 500 mA and are mostly intended for
consumer goods rather than fixed devices.
If the DLm cabinet is correctly grounded to the AC power source, leakage current not
produces a voltage leading to electrical shock. Serious insulation breakdowns trip the
breakers feeding the cabinet or, preferably first clear fuses in individual internal
modules closest to the fault.
Choosing a UPS
This section provides an overview of how to choose the correct UPS.
The VTEC and Storage Controllers (Data Movers) are stateless, so no battery backup
is required. If there is a power failure, the Storage Processor writes contents of the
write cache to disk, before shutdown. Although DLm does not require a battery
backup to ensure data integrity, to avoid potential downtime, purchase a UPS from a
qualified vendor.
Dell EMC do not offers or recommends any specific UPS suppliers or product type to
its customers. However, Dell EMC uses preferred suppliers for UPS systems in their
facilities. If you, the customer, are implementing a UPS, Dell EMC recommends the
following:
l
When you are planning the UPS solution for a DLm and the host system is
presently (or will potentially be) protected with a UPS, the battery backup time
you propose for the DLm UPS solution should match that of the host system.
l
The DLm requires independent zone B and zone A power feeds for each cabinet.
l
The UPS should be equipped with an internal output isolation transformer.
Environmental specifications and regulatory compliance
44 Disk Library for mainframe Physical Planning Guide for DLm8500
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