Insulation - Hitachi EC701HP 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 13kVA 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.
Manual Rev. 0.1 - February 2018
ALTERNATIVE NETWORK AC
RETIFIER
AC INPUT
Figure 2-1 - Example of UPS with isolating transformer
INVERTER
INSULATOR
BATTERY
AC OUTPUT
C.E.
2-2