Insulation - Hitachi EC702HP Operation Manual

Section 2 - Minimum Installation Requirements
(E-Compact ATSC Transmitters)

2.2.1.3 Insulation

It is important to provide suitable electric insulation between the shelter's power points and the
Hitachi Kokusai Linear TV transmitter, which can be achieved by means of insulating transformers.
This will hinder the passage of any kind of transient from the electric network to the TV transmitter
and vice versa. Moreover, the Hitachi Kokusai Linear TV transmitter is fitted with switching power
supplies that require a purely sinusoidal input voltage, but output voltages are usually not purely
sinusoidal if electronic stabilizers or UPS devices are used without an insulating transformer.
The insulating transformer should be dedicated to the Hitachi Kokusai Linear TV transmitter and
its capacity should be the same as that adopted for the voltage stabilizers or UPS devices, i.e.
30% above the specified TV transmitter consumption in kVA.
The Hitachi Kokusai Linear TV transmitter should not be installed within a radius of 10 meters
from the 13-kVA transformer, as it could cause interferences due to the electromagnetic field or
sparking in the internal brushes.
Recommendations:
1- We recommend that the transmitter "never sees" the electric power directly.
2- We recommend using UPSs online double conversion and / or UPSs online Delta-conversion
built with isolation transformer and power factor correction (PFC).
Advantages:
- These types of UPSs bring great protection and insulation to the transmitter due to its
mode of operation and design.
- The double conversion is due to be converted to AC power and DC to DC voltage is
converted back to AC, which eliminates any disturbance in the electric power when
converted to DC, thus protecting the transmitter.
Important to note that UPS does not necessarily need to have a battery bank, thus minimizing
the cost of the final product. This solution is much better than a conventional stabilizer due to
double conversion as explained earlier.
- The power factor correction (PFC) in the UPS is necessary to reduce the cost of electricity,
it reduces the reactive power (VAr), dimunindo the total power (VA).
Importantly, it is not efficient to have a transmitter with power factor correction (PFC) powered
by a UPS without PFC, because all the advantage achieved by the transmitter is lost on UPS,
not resulting in energy savings. When making this type of connection, you actually had a great
load (resistive behavior) to the UPS, but its electric power sees the input of the UPS (without
PFC, high consumption).
When we have a UPS with power factor correction (PFC), this will present a network for optimal
behavior (low reactive power, low consumption) even connected to a transmitter without PFC,
ie, it will correct the power factor of all the system.
Manual Rev. 0.0 – April 2016
2-2