On a transformer name plate %IZ(%Impedence) is mentioned.
What is the meaning of %IZ and how it is calculated?
Answers were Sorted based on User's Feedback
Answer / bhaskar goswami
Calculating the Short Circuit Current when there is a Transformer in the circuit. Every transformer has “ %” impedance value stamped on the nameplate. Why is it stamped? It is stamped because it is a tested value after the transformer has been manufactured. The test is as follows: A voltmeter is connected to the primary of the transformer and the secondary 3-Phase windings are bolted together with an ampere meter to read the value
of current flowing in the 3-Phase bolted fault on the secondary. The voltage is brought up in steps until the secondary full load current is reached on the ampere meter connected on the transformer secondary.
So what does this mean for a 1000KVA 13.8KV – 480Y/277V.
First you will need to know the transformer Full Load Amps
Full Load Ampere = KVA / 1.73 x L-L KV
FLA = 1000 / 1.732 x 0.48
FLA = 1,202.85
The 1000KVA 480V secondary full load ampere is 1,202A.
When the secondary ampere meter reads 1,202A and the primary Voltage Meter reads 793.5V. The percent of impedance value is 793.5 / 13800 = 0.0575. Therefore;
% Z = 0.0575 x 100 = 5.75%
Taken From:
Simple Methods for Calculating Short Circuit Current
Without a Computer
By Dennis McKeown, PE
GE Senior System Application Engineer
Is This Answer Correct ? | 4 Yes | 0 No |
Answer / k.prakashchandra
full load currentximpedance /rated voltage in %
Is This Answer Correct ? | 5 Yes | 3 No |
what is power factor? whether it should be high or low? why?
what is the capacitance of a single conductor
what is meant by substation?
what is the difference between 4pole & 6pole DC Motors & give advantage ?
various transmission tower like .,D tower ,K.C.O tower ,C.C.O tower,K.C.R tower ,C.C.R tower ,H.C.O tower in different tons.
what should be correct gas pressures to be a 1.5 ac unite
Define magnetic centre in a motor?
What is the difference between double compression
7 Answers Bhel, Hyundai, Orchid Chemicals and Pharmaceuticals, PDO, Prefamac,
what is the principal of braker
When a capcitor is used on 440 v thenthis is kvar rating 25kvar .my question is that when we use this capcitor use 480 v &525 volt .how much kvar increase . Plz give my question ans. And give answer with formula .my mail id is rohitashsaini013@gmail.com
What happens when the field of an alternator connected to infinite bus is suddenly removed?
how can service sitting be setted for MCCB?Example for sittings IR (CURRENT RATING),IS(CURRENT STARTING)IO (current operating