Information

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Product Portfolio for the Railway Sector
Application Terminology
Pre-Charge Resistor
This is used on system start up to charge the DC coupling capacitor. The resistor limits the inrush current during charging of the DC
coupling capacitor. This capacitor sits across the DC voltage source to keep the line voltage constant when the input voltage drops
low. The resistor must be able to absorb high energy from a single pulse, over a short time.
• Key Feature: Short-term overload capability
Capacitor Discharge Resistor
The resistor is fitted across the capacitor terminals to provide a safety function. When the voltage to the capacitor is removed, the
resistor discharges any residual voltage in the capacitor making it safe to touch. The resistor must handle continuous power as it
dissipates power continuously when the capacitor is connected to a voltage source.
• Key Feature: Continuous power dissipation
Inrush Limiting Resistor
Similar to precharge resistor, but offers protection to the rectifier section of circuit.
• Key Feature: Short-term overload capability
Crowbar Resistor
The resistor is used to drop the voltage to earth safely, generating a zero voltage in the circuit when a fault has been detected.
• Key Feature: Ability to absorb large short-term energy and voltage overloads, with a high insulation resistance
Balancing Resistor
The resistor is used to balance the voltage across critical components (such as IGBTs) when they are connected in series. This is to
ensure that each component has equal voltage stress during operation.
• Key Feature: Tight tolerance, low power and high ohmic value
Current Sense Resistor
A low ohmic resistor creates a small voltage drop in the circuit. As the current in the circuit changes the voltage drop will vary.
The change in voltage drop is used to measure the current to or from the circuit. This current can be monitored allowing an action
in the control software.
• Key Feature: Low ohmic value, high accuracy
Snubber Resistor
The resistor is used to absorb transient high voltage spikes produced by switching a solid state switch (like relays, IGBTs, GTOs, etc.).
It is connected in series with a capacitor across the switch. These switching operations can be very high frequency therefore the
resistor must have a low inductance, so that the transient spike is not transferred back into the switch.
• Key Feature: Dissipation of repetitive energy pulses, low inductance
Filter Resistor
This resistor makes up a RC network which is used to reduce the noise on power lines. The resistor is fitted inline with a capacitor
with one side connected to earth enabling it bleed overvoltage to ground. These resistors must be able to handle continuous power
as they are in circuit constantly as the frequency of noise is high enough to be considered constant.
• Key Feature: Continuous power dissipation
Note: Partial Discharge
A resistor with low partial discharge is a requirement of many of the applications above. Partial discharge is a form of high voltage
test that can be used to measure the life of the component. It measures the amount and size of voids in the insulation and therefore
the quality of it.
Literature No. 4-1773460-6 Dimensions are in millimeters Dimensions are shown for TE Connectivity / Berwyn, PA
Issued 3-11 and inches unless otherwise reference purposes only. For email, phone or live chat, go to: te.com/help
specified. Values in brackets Specifications subject
are standard equivalents. to change.
Rail brochure internal pages feb 11.qxd 17/3/11 13:12 Page 37