Grounding; Stability; Insulation - Hitachi E-Compact High Power Series Operation Manual

2.2. Grounding

The grounding system to which the Comark TV transmitter will be attached is suggested to
be designed and implemented by a qualified professional. An improper grounding system
may jeopardize the equipment as well as the lives-of the professionals working in the
shelter. To be considered proper, the grounding is suggested have a resistance of no more
than 5 Ohms.
It is recommended that all of the devices involved in the transmission system are that the
same potential, so that there is no DDP, favoring the equilibrium of the flow of the
atmospheric load.
It is important to state that if there is a need for chemical alteration of the soil, in order to
provide the lowest impedance, it establishes a temporary condition for not being part of the
natural chemistry of the place, thus being naturally absorbed. In this condition, preventive
soil analyzes should be conducted as preventive maintenance procedure.

2.3. Stability

The voltages in each TV Transmitter phase should be stabilized. The use of voltage
stabilizers or stabilized uninterruptible power systems (UPS's) is necessary since these
devices can protect the TV transmitter from power surges. The voltage stabilizer or UPS
design would be most effective if exclusively used with the Comark TV transmitter and is
sized to operate at least 30% above the kVA consumption specified by the TV transmitter.
For example, for the TV transmitter with maximum consumption of 38kVA, a voltage
stabilizer, or 50kVA UPS should be used.
Input voltage variations above 15% of the rated values specified for the Comark TV
transmitter may cause damage to the equipment and in this case will not be covered by the
factory warranty. In addition, it is important to check the potential difference between the
ground and neutral terminals (if any) that will be connected to the Comark TV transmitter.
This potential difference should be at most 3V.

2.4. Insulation

It is important to have isolation between the energy stations of the shelter and the TV
transmitter, which is achieved with the usage of isolator transformers. This guarantees that
no AC Mains' transient coming from the shelter will be passed on to the TV transmitter or
vice-versa. Besides, Comark's transmitters feature switching power supplies that require
purely sinusoidal power inputs and voltage regulators / no-breaks without isolator
transformers that have no assurance of a purely sinusoidal outputs. It is suggested that the
isolator transformer should also be exclusive to the transmitter and its dimensioning should
use the same standards employed in the dimensioning of the voltage regulators / no-break
(ie, at least 30% higher than the specified consumption transmitter's (KVA)).
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