ABB REL 551-C1*2.5 - Transformer Module (TRM); Design; Technical Data

140
Transformer module (TRM) Chapter 10
Hardware modules
3 Transformer module (TRM)
3.1 Design
A transformer input module can have up to 10 input transformers. The actual number depends
on the type of terminal. Terminals including only current measuring functions only have current
inputs. Fully equipped the transformer module consists of:
• Five voltage transformers
• Five current transformers
The inputs are mainly used for:
• Phase currents
• Residual current of the protected line
• Residual current of the parallel circuit (if any) for compensation of the effect of
the zero sequence mutual impedance on the fault locator measurement or residual
current of the protected line but from a parallel core used for CT circuit supervi-
sion function or independent earth fault function.
• Phase voltages
• Open delta voltage for the protected line (for an optional directional earth-fault
protection)
• Phase voltage for an optional synchronism and energizing check.
3.2 Technical data
Table 161: TRM - Energizing quantities, rated values and limits
Quantity Rated value Nominal range
Current I
r
= 1 or 5 A (0.2-30) × I
r
(0.2-15) x I
r
for line differential
function
Operative range (0.004-100) x I
r
Permissive overload 4 × I
r
cont.
100 × I
r
for 1 s
*)
Burden < 0.25 VA at I
r
= 1 or 5 A
Frequency f
r
= 50/60 Hz +/-10%
*)
max. 350 A for 1 s when COMBITEST test switch is included.